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Sixty six years ago today, had Japan not surrendered to the Allies after the dual A-Bomb attacks and the Soviet Invasion of Manchuria, the armed forces of the British Empire would have stormed the western beaches of Malaya at Port Dickson and Port Swettenham with two infantry divisions, one infantry brigade, lead by a regiment of DD-tanks and flame throwing landing vehicles. This invasion would have set off a chain of events that would have seen hundreds of thousands, if not millions, murdered and killed before the Allies put down the Imperial Japanese Armed Forces, starting with Allied Prisoners of War. The word of that atrocity would have prevented a later Japanese surrender as the British and American public’s rage would have left the American President and British Prime Minister no other options.

This is was a very near run thing as Britain’s ambassador to Japan Hugh Cortazzi (1980 to 1984) said here:

On Aug. 15, 1945, the Japanese authorities “announced that although Nippon had agreed to unconditional surrender, Field Marshal Count Terauchi, Commander in Chief of the Southern Army, did not associate himself with it and intended to fight on. What we did not know then was that a plan existed at Count Terauchi’s Saigon headquarters to execute all prisoners in case of invasion.”

This passage on page 573 of “Tennozan: The Battle of Okinawa and the Atomic Bomb“ by George Feifer, makes clear the human cost of that “Kill All” order being executed:

“After the fall of Okinawa, Field Marshal Count Hisaichi Terauchin issued an order directing his prison camp officers to kill all their captives the moment the enemy entered his southeast Asia theater. That would have been when those 200,000 British landed to retake Singapore, less than three weeks after the Japanese surrender. There was a real chance that Terauchi’s order would have been carried out, in case up to 400,000 people would have been massacred.”

And it would not have stopped there. When the British reached Singapore, it would have found a repeat of “The Rape of Nanking without wartime censorship being able to cover it up. More importantly, Allies Ultra and Magic code breaking let Allied leaders know this was on the table.

From Truman’s August 9, 1945 Radio Report to the American People on the Potsdam Conference.

I realize the tragic significance of the atomic bomb.
 
Its production and its use were not lightly undertaken by this Government. But we knew that our enemies were on the search for it. We know now how close they were to finding it. And we knew the disaster which would come to this Nation, and to all peace-loving nations, to all civilization, if they had found it first.
 
That is why we felt compelled to undertake the long and uncertain and costly labor of discovery and production.
 
We won the race of discovery against the Germans.
 
Having found the bomb we have used it. We have used it against those who attacked us without warning at Pearl Harbor, against those who have starved and beaten and executed American prisoners of war, against those who have abandoned all pretense of obeying international laws of warfare. We have used it in order to shorten the agony of war, in order to save the lives of thousands and thousands of young Americans.
 
We shall continue to use it until we completely destroy Japan’s power to make war. Only a Japanese surrender will stop us.

Emperor Hirohito took the hint and sent a personal representative known to Field Marshal Count Terauchi to get the Count to enforce a surrender on his troops.

11 Sep 2011 UPDATE (Below the Fold)

The name for this “Invasion That Never Was” — sandwiched between the Battle of Okinawa and the Planned American invasion of the Japanese Home Islands — was Operation Zipper. The plan was devised by Admiral Lord Mountbatten’s South-East Asia Command and announced in June 1945, in response to Prime Minister Churchill’s 3 February 1945 to complete the liberation of Burma as rapidly as possible and then liberating Malaya.

Mitch Williamson in his 2007 www.warandgame.info post describes Operation Zipper as follows:

Operation Zipper called for the capture of Port Swettenham on the north-west coast of Malaya leading to a southward advance on Singapore. In this sweep “Zipper” concentrated on capturing a beachhead in the Port Swettenham/Port Dickson area of south-west Malaya. The opposition was found by Field marshal Count Hisaichi Terauchi’s Southern region command, i.e. the 29th Japanese Army in Malaya under the command of General K. Doihara’s 7th Area Army. “Zipper” faced two Japanese divisions and an Independent Mixed Brigade, supported by a tank battalion, in the Kra isthmus region.

The Allied Landing Force for “Zipper” was Lt.General O.L.Robert’s XXXIV Indian Corps (5th, 23rd, 25th and 26th Indian Divisions, 3rd Commando Brigade and one Parachute Brigade of the British 6th Airborne Div.), and though “Zipper” itself was to use just two divisions and one brigade, the corps’ additional forces were to be landed as soon as possible for the advance south towards Singapore.
 
D-day for Zipper was pushed to 9 September and would have landings near Morib with the 25th Indian Division and the 37th bde of the 23rd Indian Division.
 
By D+6 (Sept 15, 1945) SEAC expected to have airfields near Port Swettenham and Port Dickson.
 
By D+8 (Sept 17, 1945), 3 divisions (23rd, 25th, and the 5th) as well as 2 infantry brigades and the 50th Indian Tank Brigade were to be there with the XXXIV Corps HQ.
 
By D+53 (Nov 6, 1945) the advance to Singapore was to be well underway.
 
To support the landings more than 500 RAF aircraft of strategic, tactical and general reconnaissance units were assembled at airfields in Burma, Ceylon and a secretly constructed Cocos Islands base.
 
At the same time the supply of arms and equipment to the underground organization in Malaya (Force 136) was intensified and photographic aircraft worked hard to provide advanced information for all three services. One of their tasks was to secure detailed pictures of the proposed landing areas, and most of this was done by a detachment of four Mosquitoes from the Cocos Islands under the control of Wing Commander Newman of No. 684 Squadron. (Trent Note — See “Mosquito photo-reconnaissance units of World War 2 By Martin W. Bowman“)

Thanks to bad weather in the first week of August 1945, and the “leaning into surrender” the A-bombings of Japan that saw Operation Zipper sisplaced by OPERATION TIDERACE occupation, the beaches for the Operation Zipper invasion were never properly photographed by photo reconnaissance planes The result was that there had 300 vehicles bogged down in the mud flats that high tide had hidden from British planes.

That problem would not have mattered in the event of a real Operation Zipper invasion.

The Japanese did not have proper “cave defense” in place to meet the invasion — with none at the landing beaches — and had very unrealistic expectations for ground unit mobility in the face of allied air superiority, plus they were expecting landings in in December 1945. They had also stripped Malaya of aircraft and maintenance crews to re-enforce Formosa in July 1945 for The American Invasion of the Home Islands.

The British looked set to go through the IJA Southern Area Armies like the Russians did in Manchuria. See this post-war article from the US Army’s “Military Review” periodical this link on the Japanese defenses and British logistical preparations for Operation Zipper, the invasion of Malaya. The Jap’s Defenses in Malaya, “The Fighting Forces” (Great Britain). page 122

However, that article does not mention the fact that all the men with 3 years and four months or longer service had been pulled from the British invasion forces. This was particularly bad for the position of coxswains running the landing craft. A lot of guys who had been in at Tunisia, Sicily, Salerno, Normandy, Southern France were pulled out right before Operation Zipper.

The BBC had an oral history retrospective a few years ago where vets involved in the administrative landing made using Operation Zipper plans described the consequences of that lack of competence. General Slim talked a great deal about the 3 year 4 month problem in his book, but said little about the coxswain issue for the Operation Zipper landing.

So the British would have had surprise and air superiority — without many Kamikazes — to get to Singapore faster than their plan, but all that would have done was find the dead city of Singapore earlier.

Thank God for the Atomic bomb.

End Notes:

The best Order of battle I have found for Operation Zipper, and most of the information for this article, came from this October 14, 2007 Mitch Williamson wargaming post.

The Sept. 11, 2011 update better reflects what was a direct copy from Mitch Williamson’s work in the body of the post and my own work.

Operation Zipper: The Invasion of Malaya, August 1945 Commonwealth Order of Battle (OOB)

HQ 14th Army
HQ XXXIV Corps

Corps Troops
11th Cavalry
25th Dragoons
1st Indian Medium Regiment
8th Sikh LAA Regiment
9th Rajput LAA Regiment
18th Field Regiment RA
208th Field Regiment RA
6th Medium Regiment RA
86th Medium Regiment RA
1st HAA Regiment, Hong Kong; Singapore Regiment RA

Major Formations
5th Indian Division
23th Indian Division
25th Indian Division
26th Indian Division
50th Indian Tank Brigade
3rd Commando Brigade
5th Parachute Brigade

Royal Navy Forces included Battleships HMS Nelson and the Free French BB Richelieu, Cruisers Nigeria, Cleopatra, Royalist and Ceylon, with the escort carriers Hunter, Stalker, Archer, Khedive, Emperor, Pursuer and Trumpeter all escorted by 15 destroyers.

Order Of Battle for the Japanese Forces in Malaya on 15 August 1945

7th Area Army (HQ Singapore)

- 29th Army (HQ Taiping)
– 94th Infantry Division (ID) (Sungei Patani)
– 35th Independent Mixed Brigade (IMB) (Port Blair)
– 36th IMB (Car Nicobar)
– 37th IMB (Camorta/Nicobar)
– 70th IMB (Kuala Kangsar)

Directly under 7th Area Army:
—- 46th ID (Kluang)
—- 26th IMB (Singapore

3d Air Army (HQ Singapore)
- 55th Flying Training Division (Singapore)

46th Division:-
123rd Infantry regiment
145th Infantry regiment
147th Infantry regiment
46th Tank unit
46th Transport regiment
Army division communication unit

94th Division:-

94th Infantry group:
256th Infantry regiment
257th Infantry regiment
258th Infantry regiment

94th Field artillery regiment
94th Engineer regiment
94th Transport regiment
Army division communication unit

26th IMB:-

146th Independent infantry battalion
147th Independent infantry battalion
148th Independent infantry battalion
149th Independent infantry battalion
Brigade artillery troops
Brigade engineer unit
Brigade communication unit

35th IMB:-
251st Independent infantry battalion
252nd Independent infantry battalion
253rd Independent infantry battalion
254th Independent infantry battalion
255th Independent infantry battalion
256th Independent infantry battalion
257th Independent infantry battalion
Brigade artillery troops
Brigade engineer unit
Brigade communication unit

36th IMB:-
258th Independent infantry battalion
259th Independent infantry battalion
260th Independent infantry battalion
261st Independent infantry battalion
Brigade artillery troops
Brigade engineer unit
Brigade communication unit

37th IMB:-

262nd Independent infantry battalion
263rd Independent infantry battalion
264th Independent infantry battalion
265th Independent infantry battalion
Brigade artillery troops
Brigade engineer unit
Brigade communication unit

70th IMB:-

428th Independent infantry battalion
429th Independent infantry battalion
430th Independent infantry battalion
431st Independent infantry battalion
Brigade tank unit
Brigade artillery troops
Brigade engineer unit
Brigade communication unit

Information on the Japanese Army Air Force (JAAF) and the Japanese Naval Air Force (JNAF) as of July – August 1945:

JAAF

3d Air Army (HQ Singapore)

- 1st Field Replacement Flying Unit (elements at Kluang, Kajang, Ipoh and Tengah – NATE, OSCAR, TONY, TOJO, LILY, DINAH, SALLY)

- 71st Independent Flying Squadron (elements occasionally at Car Nicobar – OSCARs and TOJOs)

- 55th Flying Training Division (Singapore)

– 107th Flight Training Brigade (Ipoh)
— 2d Flight Training Unit (Sungei Patani – Ki-54, Ki-79, IDA light bomber training)
— 3d Flight Training Unit (Taiping – Ki-54, IDA, SONIA reconnaissance training)
— 12th Flight Training Unit (Alor Star – Ki-55, Ki-79, IDA, NATE, OSCAR fighter training)
— 28th Operational Flight Training Unit (Ipoh – Ki-54, PEGGY bomber training)
– 109th Flight Training Brigade (Kuala Lumpur)
— 2d (Renshu) Flight Training Unit (Kluang – Ki-55, Ki-79, IDA reconnaissance training)
— 44th Flight Training Unit (Kuala Lumpur – Ki-55, Ki-79, IDA fighter training)
— 45th Flight Training Unit (Khota Bharu – Ki-54, IDA reconnaissance training)
— 17th Operational Flight Training Unit (Singapore – IDA, SONIA, OSCAR fighter training)

15th Air Sector Command (Singapore-Kallang)
27th Airfield Bn. (Singapore-Changi)
85th Airfield Bn. (Sungei Patani)
101st Airfield Bn. (Alor Star)
16th Airfield Co. (Singapore-Tengah)
28th Airfield Co. (Singapore-Kallang)
20th Field Air Supply Depot (Singapore)
16th Field Air Repair Depot (Singapore)
3d Air Signal Command (Singapore)
3d Air Signal Brigade (Singapore)
11th Air Signal Regiment (Singapore)
3d Air Fixed Signal Unit (Singapore)
33d Ground-to-Air Radio Unit (Sungei Patani)
3d Meteorological Regiment (Singapore)

JNAF

13th Air Fleet (Singapore)

- 936 Kokutai (Singapore-Seletar – 17 JAKE and 7 PETE floatplanes)
- Malay Airfield Unit (Singapore-Seletar – controlled all JNAF airfields in Malaya)

(JNAF ground organization omitted)

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A belated happy Victory over Japan Day.

On August 14th in 1945 Imperial Japan accepted the terms of the Potsdam Declaration and averted Operation Downfall, the two stage invasion of Japan. This invasion would have resulted in at least a million American casualties and likely millions of Japanese dead from direct effects of the invasion plus the mass starvation that would have been sure to occur in its aftermath.

The best web site presentation on the “Invasion that Never Was” I have found is here.

See the PDF copies of the original documents plus some HTML remapping of the same documents courtesy of the alternatewars.com web site.

Were it not for the two atom bombings and the Soviet invasion of Manchuria shocking the Imperial Japanese into surrender, many of us would not be here today because our parents and grandparents would have died on the shores of Kyushu and Honshu.

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Richard Fernandez, AKA blogger Wretchard the Cat, has a post on Pajamas Media titled The Foundations of Our World on the modern politically correct myths surrounding Hiroshima — America was the original “nuclear sinner” and war criminal while Japan was “innocent victim” — that have become “The Narrative” that the Ruling classes promulgate through the Western education establishment and main stream media.

Just because this is “The Narrative” does not make it the objective truth. There is still a lot of historical information still being unearthed about that era. Information highly destructive of the politically correct narrative in the form of the unearthed history of the Japanese chemical warfare program.

The bottom line up front is that Hiroshima was a center of chemical weapons production for the Japanese and the weapons produced there were used in against Chinese, British and American troops in World War Two.

This is from October 3,1998 edition of the The Okinawa Times, and posted at the http://forum.axishistory.com

An unexploded poisonous gas weapon of the Imperial Japanese Army was found in the remains of an underground Japanese Army hospital used during the land battle on Okinawa in WWII. Although there were no reports of victims of poisonous ordnance during the battle, the finding was testimony that the Japanese Army planned to use poison in defense of Okinawa against the U.S. invasion. The secret grim operation of poison gas use during WWII was excavated after a fifty-three year silence.
 
Isamu Kuniyoshi, 59, is a man who volunteers on his own to excavate the ruins of War shelters in order to show people the cruelty of war by exhibiting various uncovered articles. In middle of July, as he was looking for War remains in the ruins of Arakaki Army Hospital in Itoman City, he found a glass ball ten centimeters in diameter. The underground hospital was like a deep foxhole, two meters high and extending a hundred twenty meters in length. Kuniyoshi encountered the poisonous weapon, without any gas, about seventy meters from the entrance while digging in the dirt with a scoop.
 
The explosive was a grenade supposedly containing hydrogen cyanide, known as “chabin,” a teapot in Japanese named after its shape. The article was sent to Kanagawa University for chemical analysis and copper powder, a stabilizing material for cyanide, was found in the glass container. According to Professor Tadaomi Nishikubo, about eighty percent of the ingredients was copper powder which was intentionally put in the glass ball for some reason. Professor Keiichi Tsuneishi, who has studied poisonous gas weapons of the Imperial Japanese Army, commented “From the shape and the copper powder, we can say it is a chabin. It proves that poisonous gas weapons were assigned to Okinawa during the War.” The professor explained that it was the first discovery of chabin at a battle site in War history.
 
The Japanese Army secretariat worked on the research and development of poison gas weapons. A hydrogen cyanide grenade, the chabin, was used in anti-tank operations. A soldier would throw the grenade into the air vent of a tank. Because the soldier had to get as close as possible, the operation was considered a suicide attack. The British Army had recorded that chabin were used in the Burma Campaign and also in China. There had been no reports of poisonous gas being used in the Okinawa Campaign.
 
The Japanese Army had produced three hundred thirty thousand chabin in Hiroshima and Tokyo by the end of WWII. According to testimonies of those who worked in a chemical factory, chabin were secretly sent to China, Taiwan, the Philippines and Singapore. There was no record of poison gas on Okinawa.
 
Information on poison gas weaponry was hidden or abandoned in order to escape international accusation at the end of the War, but tracing the relationship between the Okinawa Campaign and poison gas has just been initiated by the event of Kuniyoshi’s excavation.

This is a technical evaluation of the Japanese hydrocyanic acid “chabin” weapon:

T. I. B.Vol. 4 No. 3
May – Jun 1999
Page 12
 
From our past:
 
A question was asked about a Japanese hand grenade. Gordon Rottman sent in this response:
 
The weapon in question is as follows (extracted from my WWII grenade book):
 
Model 1 Frangible Toxic Gas Hand Grenade (SEISAN SHURUDAN) Glass gas grenades were captured on Guadalcanal and in Burma early in the war. Its designation is unconfirmed and is believed to have actually been developed in the 1930s. They were also identified as “T.B. grenades” by Allied intelligence, but the meaning is unknown. These are the gas grenades once employed against British tanks in Burma near Imphal in 1942. They were filled with liquid hydrocyanic acid (AC), a blood gas derived from hydrogen cyanide. These grenades were initially reported as filled with 80 percent hydrogen cyanide (aka prussic acid). They were found stabilized with either powdered copper (Cu) or arsenic trichloride (AsCl3). Both types had metal crown caps. The copper-stabilized type had a rounded bottom with a cork plug and the other a flat bottom and a rubber plug under the caps. The copper-stabilized type was packed in a metal can and the second in a cylindrical cardboard container. Both types were further packed individually in larger cylindrical metal cans with a web carrying strap. The inner containers were double walled (sides, bottom, and lid) and filled with neutralizing agent-soaked sawdust. The arsenic trichloride-stabilized type were called the 172 B-K and 172 C-K by Allied intelligence after container markings, but these were almost certainly lot numbers rather than designations. (In early 1943, the US Military Intelligence Division reported a similar grenade being used by the Germans, but this turned out to be a mistake due to misidentification of Japanese grenades captured on Guadalcanal and returned to the States where they were mixed up.)
 
Weight: 1.2 lbs Diameter: 3.9 in
 
Construction: glass body, steel cap Filler: 12.2 oz liquid hydrocyanic acid with stabilizer
Fuze: none
Causality Radius: INA
 
Identification: clear glass body, yellowish (copper-stabilized) or greenish (arsenic trichloride-stabilized) liquid, light olive drab shipping can with brown band
Fig. 9-18
 
There was also a glass screening smoke grenade of similar design. Yes, it is in violation of the Hague Convention, but so was mistreatment of POWs. Gordon Rottman

I have tracked at least three instances of the Japanese using this weapon against the Anglo-Americans.

The British 7th Queen’s Own Hussars Regiment in Imphal Burma was close assaulted by Japanese infantry armed in with these “Chabin” gas weapons 1942.

American Army troops in Guadalcanal were hit with them on two separate occasions on 23 and 28 January 1943. Both incidences were described as “Desperate acts by individual soldiers” in the histories I researched.

Significant stocks of Japanese chemical weapons were captured in Leyte by American Army units and both the Japanese Army and Navy used chemical weapons against American forces in Luzon, despite official orders in the name of the Emperor not too.

The 1st Cavalry Division was hit several times by hand held and 75mm field gun fired chemical munitions in Manila in February 1945. It is not clear from the US 6th Army field reports I have read it it was Japanese Army or Navy ground troops who were the culprits.

Finally, Filipino Guerrilla’s reported to US 6th Army in January – February 1945 that the Japanese garrison in Davao, Mindanao had planted mustard gas land mines and tested the blood agent AC in Chabin hand grenades on dogs.

The American Army “Victor V” river campaign from Illana Bay in Western Mindanao to Davao by General Eichelberger is much more easily explained by his need to avoid those mustard gas mine fields on the beaches and bridges of Davao.

All this new information won’t make a difference to those carrying and deeply invested in the old narrative, but it will make a difference to you the reader, if you are willing to look at the past with an open mind.

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These are post strike USAAF photo of the Aug 06, 1945 atomic bomb attack on Hiroshima

The best way I can think of to commemorate the 65th anniversary of the the atomic bombing of Hiroshima is to review an article by historian Richard B. Frank that was published in the Weekly Standard in 2005. In it, Frank lays out the competing visions of history that have grown up after the event, and its most recent turns, that refresh our understanding of that day.

Why Truman Dropped the Bomb
Sixty years after Hiroshima, we now have the secret intercepts that influenced his decision.
by Richard B. Frank
08/08/2005, Volume 010, Issue 44
 
The sixtieth anniversary of Hiroshima seems to be shaping up as a subdued affair–though not for any lack of significance. A survey of news editors in 1999 ranked the dropping of the atomic bomb on August 6, 1945, first among the top one hundred stories of the twentieth century. And any thoughtful list of controversies in American history would place it near the top again. It was not always so. In 1945, an overwhelming majority of Americans regarded as a matter of course that the United States had used atomic bombs to end the Pacific war. They further believed that those bombs had actually ended the war and saved countless lives. This set of beliefs is now sometimes labeled by academic historians the “traditionalist” view. One unkindly dubbed it the “patriotic orthodoxy.”
 
But in the 1960s, what were previously modest and scattered challenges of the decision to use the bombs began to crystallize into a rival canon. The challengers were branded “revisionists,” but this is inapt. Any historian who gains possession of significant new evidence has a duty to revise his appreciation of the relevant events. These challengers are better termed critics.
 
The critics share three fundamental premises. The first is that Japan’s situation in 1945 was catastrophically hopeless. The second is that Japan’s leaders recognized that fact and were seeking to surrender in the summer of 1945. The third is that thanks to decoded Japanese diplomatic messages, American leaders knew that Japan was about to surrender when they unleashed needless nuclear devastation. The critics divide over what prompted the decision to drop the bombs in spite of the impending surrender, with the most provocative arguments focusing on Washington’s desire to intimidate the Kremlin. Among an important stratum of American society–and still more perhaps abroad–the critics’ interpretation displaced the traditionalist view.
 
These rival narratives clashed in a major battle over the exhibition of the Enola Gay, the airplane from which the bomb was dropped on Hiroshima, at the Smithsonian Institution in 1995. That confrontation froze many people’s understanding of the competing views. Since then, however, a sheaf of new archival discoveries and publications has expanded our understanding of the events of August 1945. This new evidence requires serious revision of the terms of the debate. What is perhaps the most interesting feature of the new findings is that they make a case President Harry S. Truman deliberately chose not to make publicly in defense of his decision to use the bomb.

I hope the last line whets your curiosity enough to go to the link and finish reading the article.

It is well worth your time.

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The fighting on Okinawa saw many M4 Sherman tanks destroyed by the improved Japanese anti-tank defense build around the 47mm Type 01 anti-tank gun. Mid-May 1945 the US Army Ordnance branch took upon itself the task to send 12 of the Sherman’s successor tank, the M26 Pershing, to Okinawa. In my previous post on the priority shipments to Okinawa spoke of a LCT convoy from Okinawa to Hawaii to pick up M26 Pershings on Hawaii.

That story was wrong.

Korean War Mail Delivery, M26 Pershing Style

I found several references after that post including Kenneth Estes’ MARINES UNDER ARMOR: The Marine Corps ans Armored fighting Vehicles, 1916-2000 that had dates of Pershing Delivery varying from 21 July to 31 July 1945. It turns the 31 July 1945 date is correct and the landing craft tank (LCT) I mentioned were at Okinawa the whole time, not in a round trip convoy to Hawaii.

The following story of the shipment of 12 Pershings to Okinawa is from PERSHING: A History of the Medium Tank T20 Series by R.P. Hunnicutt:

Mid May 1945 – A Ordnance “Mission” similar to the “Zebra Mission” sent to Europe with the M26 Pershing was organized by Brig. Gen Borden, Chief of the New Developments Division, Wash. D.C. Twelve M26 Pershings were to be delivered to Naha, Okinawa with tools, maintenance crews, spare parts and other equipment.

A column of Pershing tanks from the Zebra Mission, March-May 1945, in Germany.

24 May 1945 — Previous Ordnance mission veterans Captain’s Gray and Taus arrive at the port of Seattle, Washington with 12 Pershings and organized the provisioning of spare engines and transmissions plus other equipment from two Pershings at the Richmond Tank Depot.

31 May 1945 – The fast freighter S.S. Katherine D. Sherwood Departs Seattle for Naha, Okinawa with a 30 June 1945 estimated arrival date with intermediate stops at Eniwetok and Ulithi Atolls.

27 June 1945 — Depart Eniwetok for Ulithi forward amphibious staging area after 10 day delay due to priority issues that finally required direct radio communication from commanding General Ordnance General Barnes and 10th Army Chief Ordnance officer, Col. Colby.

12 July 1945 — Depart Ulithi for Okinawa after 12 day delay that required a direct letter from Ordnance Captain’s Gray and Taus to new commanding General, 10th Army, General Stillwell to clear the bureaucratic log jam.

21 July 1945 — The Pershing mission arrives at Naha and hits a final delay. The LCT-5 landing craft cannot carry a M26 Pershing. It is too wide. So LCT-6 landing craft have to be obtained. This delays landing of Pershings.

30 July 1945 — The S.S. Sherwood finally lands two of the 12 M26 Pershings. The two more are landed the next day, then the SS Sherwood must leave the area due to a Typhoon that wrecks much of Okinawa.

4 August 1945 — The SS Sherwood returns to Naha and finally delivers the last eight Pershings. Training begins with the 193td and 711th Tank Battalions and the 81st and 293rd Heavy Maintenance Battalions.

10 August 1945 — After the first class with the above units is conducted, further training is halted and the Ordnance mission is placed on stand by as the 10th Army is being alerted for the “Operation Black List” Japanese occupation landings.

15 August 1945 — V-J Day arrives and the Pershing mission is canceled.

This M26 tank is fighting in Korea near the Naktong River

In addition to looking for the above, I spent some time tracking down what formations were going to have Pershings for the Operation Downfall landings on Kyushu and Honshu now have a good idea what formations the M26 would be located:

1) The Pershings provided for combat training with the 193rd and 711th Tank Battalions were for Operation Coronet. The 193rd would be with the 27th Infantry and and the 711th would be with the 7th Infantry Divisions respectively — assuming these Pershings were not taken earlier as replacements for lost tanks on Kyushu.

2) DOWNFALL — The End of The Imperial Japanese Empire, by Richard Frank, Page 398, said 125 Pershings shipped from the USA would be issued as follows:

o 706th Tank Btn — 71xM26 Pershings in four medium tank companies and 6xM4A3(105mm) Shermans in a platoon in headquarters and headquarters company.
.
o 767th Tank Btn — 54xM26 Pershing in three medium tank companies, 17 M24 Chaffee in a light tank company and 6xM4A3(105mm) Shermans headquarters and headquarters company

The 706th Tank Battalion was on Luzon and had supported the 77th Infantry Division on Okinawa. If that relationship held for Operation Olympic, that would put the 706th on the beaches of Kaiman-Dake with the IX (9th) Corps on X+3 (4 Nov 1945).

The 767th Tank Battalion was on Hawaii and was slated to land with the 98th Infantry Division, which was also part of IX Corps as it’s reserve. However, the 98th ID was also tasked to be the contingency reserve to support any landing beach so it could have arrived as reinforcements to the US Army I (1st) Corps at the beaches of Miyazaki, the US Army VI (11th) Corps at the beaches of Shibushi in the Ariake Wan, or with the USMC V (5th) Amphibious Corps on the beaches near Kushikino.

Details like this are important for a couple of reasons.

First, the M26 Pershing was invulnerable on the front hull and front turret to the Japanese 47mm type 01 anti tank gun and the gun had to be at 100 meters or closer for the armor piercing shell to have a chance at either turret side or hull sides forward of the engine compartment.

Second, the Japanese were about to introduce their own technological surprise for Operation Downfall — Japanese version of the Bazooka.

While the Type 4 70mm rocket launcher could not penetrate the front or sides of a Pershing at any range and had to hit in the rear engine compartment or tracks to be able to do any damage to a Pershing. It could penetrate the side and rear of the of the Sherman’s turret or hull as well as any portion of the heavy 155mm, 8-inch (203mm) and 240mm self-propelled guns the US Army was going to land to crack Japanese fortifications.

For the “Cave processing” tactics that the USMC developed on Okinawa to work in Kyushu for the American landing forces. They needed a tank that had the armor to survive close-in to Japanese Type 4 hunter-killer teams.

The Pershing would be that tank.

Update 28 June 2010:

I checked Shelby Stanton’s “WORLD WAR II ORDER OF BATTLE” for the US Army last night and found that the 77th Infantry Division was in Cebu and not Luzon in the Philippines.

This implies to me that the Pershing armed 706th Tank Battalion would be landing with either or both the I Corp or IX Corps on Operation Olympic’s X-day, since the four US Army assault divisions in the first wave of the landings were staging from Luzon.

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I ran across more data on the priority shipping CDL Tanks and deploying Recoilless Rifles for Okinawa that made some of the things I posted my here factually wrong. There was also additional information of the “VT” proximity fuse in US Army artillery.

Taken together, what didn’t make it to Okinawa would amount to a technological surprise for the Japanese defending the beaches of Kyushu, had the A-bomb failed to get a surrender.

The M3 CDL tanks were assembled at Rock Island Arsenal. Instead of a main gun turret the tank chassis mounted a steel box containing a 13 million candle power carbon arc lamp backed by mirrors to focus the beam, a machine gun and fake cannon. A 10Kw generator was mounted on the back and run by a power take off from the engine. The 75mm sponson gun was retained. Some 500 M3 CDLs were produced in 1943-44. Some 300 entered US Army service with a few used during the battle for the Ludendorff Bridge at Remagen, Germany. Eighteen CDL arrived on Okinawa in June 1945 after the fighting ended

First, it turns out that the June 1945 arrival of the M3 Grant medium tank based “Canal Defense Light” (CDL) tanks was not based on a April 1945 emergency request during Okinawa fighting like the Pershing, but instead was due to a trip by a US Army Ordnance officer working for 10th Army to Washington DC months earlier.
See below:

ON BEACHHEAD AND BATTLEFRONT
Chapter 23, pages 453-453

What of New Weapons?

Colonel Daniels thought good use could be made of Canal Defense Light tanks. The Japanese in their campaign in Malaya had successfully made end runs at night along the coast, landing tanks from boats, and could be expected to do the same thing along the coast of Okinawa. Against such attacks, the CDL’s with their blinding searchlights might be used to very good effect. General Buckner had never heard of the CDL’s but after having been furnished a description he gave Daniels permission for a flight to Washington to round up a company. When Daniels got to Washington, he found that all of these special tanks had gone to England for shipment to France, but that he might expect some in several months. Accordingly, he put in a request for about 18 or 20 CDL’s, and an officer and men trained in operating them. They did not arrive until late June 1945, after the Okinawa campaign was over.25
.
25. Ltr, Brig Gen Robert W. Daniels to Lida Mayo, 23 Nov 63, OCMH. When the CDL’s arrived Daniels got one ashore and showed it to Gen. Joseph W. Stilwell, who had succeeded Buckner as Commanding General of Tenth Army. Stilwell was impressed. Ibid.

Second, the same section in ON BEACHHEAD AND BATTLEFRONT also provided more information on the recoiless rifiles used in the Okinawa campaign. It gives a lower number of recoilless rifles in Okinawa than I remember reading and it provides numbers for how many went to Europe versus Okinawa.

Not only on tanks and artillery but on new items such as the 57-mm. and 75-mm. recoilless rifles and VT fuzes, Europe had priority. In March 1945 the Ordnance Department sent fifty of each caliber recoilless rifle to Europe, with ammunition and instructors, for special operational use. The best Tenth Army Ordnance could do was to obtain a promise that a demonstration team would be sent to Okinawa after the invasion. The team arrived with two recoilless rifles of each type on 19 May 1945. In late April a team arrived to demonstrate the use of VT fuzes in ground combat (first used in this manner in the Ardennes), one of several teams sent to the Pacific that spring. Neither the recoilless rifle nor the VT fuze had any real effect on the outcome of the Okinawa campaign.(26)
.
and
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26. (1) Col. Rene R. Studler, “Recoilless Rifles,” Army Ordnance , XXIX, no. 152 (September-October 1941), p. 233. (2) Rpt Ord Officer Tenth Army, Annex E, pp. 7-8; Annex C, p. 14. (3) Combat Analysis Sec, Opns Div, WDGS, Extracts from Operations Reports on Reduction of Japanese Cave-type Fortifications, Part II, 1 Jun 45, p. 2. (4) Memo, Col Rene R. Studler for Chief Research and Development Service, OCO, 16 Jun 45. Last two in Folder, Cave Warfare, Barnes File, OHF. (5) For difficulties with the VT fuze see Ordnance Periodic Summaries, Tenth Army, 29 Apr- 10 Jun 45, Folder, 0-765-8, POA, 29 Apr 45, OHF.</

M-18 57mm Recoilless Rifle in Korean War hill fighting similar to that which American Infantry would have seen in Nov/Dec 1945 Kyushu

I also found this link at Ask.com on M18 57mm Recoilless Rifles that had the following information:

In late 1944, the T15 was redesignated the M18 57-mm Recoilless. The cannon and 57-mm ammunition were placed in mass production. Four types of ammunition were initially produced: an antitank HEAT round, an HE round, a smoke shell using white phosphorus, and a training round.[6][7] By early 1945, over 2,000 M18 recoilless rifles and 800,000 rounds of ammunition were on order.[8]
.
The first production M18 57-mm cannons and ammunition were rushed from the factories to the European and Pacific war theaters. The first combat the new cannon saw was with the U.S. Army’s 17th Airborne Division near Essen, Germany. While impressed with the fire power available in a lightweight weapon with the HE round, the M18′s 57mm HEAT round was a disappointment with only 63.5mm of penetration,[9] compared with the older M1A1 Bazooka which had a penetration of nearly 120mm.[10][11] The reason for the disappointing penetration by the M18′s 57-mm HEAT round was the problem any HEAT round will have if it is fired from a cannon that uses rifling to stabilize the projectile after it leaves the muzzle. Spinning degrades the penetration of HEAT rounds.[12]
.
In the Pacific Theater, the new lightweight 57mm cannon was an absolute success as “pocket artillery” for the soldiers of U.S. Army infantry units that were issued the M18. It was first used in the Pacific Theater during the Battle of Okinawa on June 9, 1945, and proved with its HE and WP rounds it was the perfect weapon for the hard fighting that took place against the dug-in apanese in the hills of that island. The only complaint the U.S. Army had was the lack of sufficient 57-mm ammunition for the M18.[13]

M20 75-mm. Recoilless Rifle in Action during the Korean War

A US Army “R-Table” infantry regiment mentioned in US Army Green Book “Organization of Ground Combat Troops” had 18 75mm recoilless rifles and 27 57mm recoilless rifles and there were three infantry regiments in each infantry division.

Based on the above Ask.com numbers, it looks highly likely the Recoilless Rifle Teams were going to happen for a significant portion, if not all, of the Operation Olympic US Army assault divisions.

By way of comparison, a 2.36 inch (70mm) Bazooka had a launch speed of 82 m/s (270 fps) while a M-18 57mm (2.26 inch) recoilless rifle had a launch velocity of 365 m/s (~1,200 fps).
This meant that the Bazooka had a maximum range of about 300 yards and an effective range of 50 yards while the M-18 had a maximum range of 3,976 m (4,300 yards) and an effective range on the order of 400 meters (430 yards). So the ability of American troops with recoilless rifles to “process” Japanese cave fighting positions for an Operation Olympic assault on Kyushu went up dramatically compared to Okinawa.

Last, the US Navy used the VT fuse extensively to shoot down Japanese airplanes, and the US Army used it for attacking ground targets starting during the “Battle of the Bulge” in Belgium during December 1944. I was unaware until I found this passage that they were not used on Okinawa to shoot at Japanese ground troops. The straight forward implication of that is that the effectiveness of American artillery for the Kyushu landings in Nov/Dec 1945 was going to go up radically whenever the Japanese came out into the open.

And the Japanese would have come into the open for their planned night time counter attacks on American beach heads and also to destroy American tanks with suicide anti-tank squads. Especially since their primary anti-tank gun, the 47mm, could not penetrate the front or sides of US M26 Pershing tank. (The story of the botched deployment of the M26 Pershing to Okinawa is the subject of another post in this series.)

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21 June 1945

On Okinawa, the Japanese headquarters on Hill 89 is taken by the forces of the US 32nd Infantry Regiment, part of US 7th Division. The body of General Ushijima, commanding the Japanese 32nd Army is found nearby.

Five hours after 10th Army commander USMC Major General Geiger declares Okinawa “Secure” the Japanese high command delivered its last kikusui or “Floating Chrysanthemum” suicide strike of the Okinawa campaign.

Several Kamikaze slip through and strike ships at the at the Kerma Ritto anchorage. Sea Plane tenders Kenneth Whiting and Curtis are both struck and the Curtis is heavily damaged by fire.

LSM-59 is hit and sunk towing the hulk of the decommissioned USS Barry, which is also sunk in the same attack. The Barry’s new mission was to be a kamikaze decoy, for which it succeeded sooner than intended.

RAISING THE AMERICAN FLAG on 22 June denoted the end of organized Japanese resistance.

22 June 1945

The US Navy suffers a suicide strike on LSM-213 at Kimmu Wan. The landing ship suffers heavy structural damage with three killed and 10 wounded.

At Nakagusuku Wan the beached LST-534 suffers a bow door strike from a Kamikaze with three killed and 35 wounded. The nearby USS Ellyson is near missed by a Kamikaze with one killed and four wounded.

Radar Picket Station 15, with USS Massey and USS Dyson present, is heavily attacked, but the fighter cover killed 29 out of an estimated 40 attackers without damage to either ship.

On Okinawa, the battle with organized ground forces has ended. The 10th Army starts a 10 plan to mop up remaining unorganized Japanese ground forces.

American forces have lost 12,500 dead and 35,500 wounded.

In the air, the American forces have lost 763 planes.

The Japanese losses include 120,000 military and 42,000 civilian dead.

For the first time in the war, there are a relatively large number of Japanese prisoners: 10,755.

American reports claim the Japanese have lost 7,830 planes.

Including today’s suicide strikes, the US Navy had 36 ships sunk and 368 damaged by the end of the Okinawa campaign.

Okinawa Background — The Death of Generals Ushijima and Cho

The following is from OKINAWA:THE LAST BATTLE by Roy E. Appleman, James M. Burns Russell A. Gugeler, and John Stevens

General Ushijima radioed his last message to Imperial Headquarters on the evening of 21 June. The impetuous General Cho made a last appeal for all units to fight to the utmost. He also prepared several messages which he hoped his secretary could eventually deliver in Japan. “Our strategy, tactics, and technics,” he explained, “all were used to the utmost and we fought valiantly, but it was as nothing before the material strength of the enemy.” 28 Realizing that they could hold out no longer, Generals Ushijima and Cho made ready for death. Their cook prepared an especially large meal to be served shortly before midnight. When the meal was finished, the two generals and their staff drank numerous farewell toasts with the remaining bottles of Scotch whisky which had been carried from Shuri. The rest of the story is told by a prisoner who learned the details of the death of Ushijima and Cho from other prisoners:
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Alas! The Stars of the Generals have fallen with the setting of the waning moon over Mabuni . . . .
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The pale moon shimmers bluish white over the waters of the southern sea, but on Hill 89 which juts abruptly from the reefs, the rocks and boulders are dyed crimson by the blood of the penetration unit which, with burning patriotism, rush the American positions for the last stand. The surrounding area displays a picture of concentrated fireworks; bursts of naval gun fire, flashes of mortar and artillery fire, to which is added the occasional chatter of machine guns . . . .
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Gathered around their section chiefs, members of each section bow in veneration toward the eastern sky and the cheer of “long live the Emperor” echoes among the boulders . . . .
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The faces of all are flushed with deep emotion and tears fall upon ragged uniforms, soiled with the dirt and grime of battle . . . .
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Four o’clock, the final hour of Hara-kiri; the Commanding General, dressed in full field uniform, and the Chief of Staff in a white kimono appeared . . . . The Chief of Staff says as he leaves the cave first, “Well, Commanding General Ushijima, as the way may be dark, I, Cho, will lead the way.”
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The Commanding General replies, “Please do so, and I’ll take along my fan since it is getting warm.” Saying this he picked up his Okinawa-made Kuba fan and walked out quietly fanning himself . . . .
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The moon, which had been shining until now, sinks below the waves of the western sea. Dawn has not yet arrived and, at 0410, the generals appeared at the mouth of the cave.
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The American forces were only three meters away [sic.].
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Four meters away from the mouth of the cave a sheet of white cloth is placed on a quilt; this is the ritual place for the two Generals to commit Hara-kiri. The Commanding General and the Chief of Staff sit down on the quilt, bow in reverence towards the eastern sky, and Adjutant J. respectfully presents the sword. Finally, the time for the honored rites of Hara-kiri arrives.
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At this time several grenades were hurled near this solemn scene by the enemy troops who observed movements taking place beneath them.
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A simultaneous shout and a flash of a sword, then another repeated shout and a flash, and both Generals had nobly accomplished their last duty to their Emperor . . . .
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All is quiet after the cessation of gunfire and smoke; and the full moon is once again gleaming over the waves of the southern sea. Hill 89 of Mabuni will live in memory forever.29

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19 June 1945

On Okinawa, the insistent use of propaganda by means of leaflets and loudspeakers, by the American forces, induces some 343 Japanese troops to surrender.

Japanese forces fall back in some disorder along the frontage of the US 3rd Amphibious Corps but continue to resist along the line held by the US 24th Corps.

FIGHTING TOWARD HILL 89, tanks of the 769th Tank Battalion attack a bypassed Japanese strong point on top of Yaeju-Dake, 18 June 1945

20 June 1945

On Okinawa, Japanese resistance along the center of the line, held by the US 24th Corps, continues to be strong.

The US 32nd Infantry Regiment (US 7th Division) reaches Height 89, near Mabuni, where the Japanese headquarters have been identified.

On the flanks, the American Marines on the right and the infantry on the left advance virtually unopposed, capturing over 1000 Japanese and reaching the southern coast of the island at several points.

The scale of surrenders is unprecedented for the forces of the Imperial Army.

Okinawa Background — Japanese Resistance Collapses

The Left and Right flank’s of the Japanese Kiyan line have collapsed. The USMC 3rd Corps put the 8th Marine Regiment of the 2nd Marine Division into the line (on the Japanese Left) fresh with A company 2nd Tank battalion and the 2nd Amtrac Battalion in support. The effect of fresh American troops on the punch drunk and under armed Japanese service troops was immediate and decisive. The 10th Army broke through on both flanks and naval gunfire had to be stopped for fear of hitting friendly troops.

This use of a fresh regiment towards the end of a campaign was a lesson learned for the USMC from Iwo Jima, when they saw the casualty figures from feeding in inexperienced replacements into units that had been in contact for too long.

The US Army had seen the same problem in Europe fighting the Germans and had reached a similar conclusion. The War Department had essentially recreated the World War One four infantry regiment division in it’s manpower plans for both Operations Olympic and Coronet.

After Okinawa 65

Now that the 65th anniversary of the Battle of Okinawa’s “Mop-up Phase” is about to start. I plan on doing a series of posts on Okinawa’s “School House of War” for US military planners and political leaders between now and the dropping of the first A-bomb.

I an going to touch on a number of subjects including the tactical lessons learned, planned American anti-Kamikaze countermeasures for the Kyushu landings, Japanese Military Leader’s plans to murder all Allied Prisoners of war and over run Allied civilians and the little touched on opposing chemical warfare postures of Japan and the Allies.

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16 June 1945

On Okinawa, Mount Yuza is captured by the US 381st Infantry Regiment. Fighting continues on the south of the island.

At sea, the Japanese air offensive against American ships slackens, but the Japanese still sink 1 destroyer and damage 1 escort carrier.

The destroyer, the USS Twiggs, was struck close to shore at twilight on bombardment duty by a low level torpedo plane. Her crew had 188 survivors with 126 men lost, dead and missing, including her captain.

17 June 1945

On Okinawa, reinforced American units advance in the Kuishi Ridge area which has been stubbornly defended by forces of the Japanese 32nd Army.

Along the line of the US 24th Corps, the last Japanese defensive line is broken. The US 7th Division completes the capture of Hills 153 and 115.

YUZA PEAK, under attack by the 382d Infantry, 96th Division. Tanks are working on the caves and tunnel system at base ridge of ridge.

The commander of the Japanese naval base on Okinawa, Admiral Minoru Ota, is found dead, having committed suicide.

18 June 1945

On Okinawa, the remnants of the Japanese 32nd Army continue to offer determined resistance to attacks of the US 3rd Amphibious Corps and the US 24th Corps.

Lt. General Simon Bolivar Buckner, commanding US 10th Army, is killed by Japanese artillery fire while he is on a visit to the front line, inspecting troops of the US 8th Marine Regiment.

Buckner is temporarily replaced by USMC General Geiger, commanding the US 3rd Amphibious Corps.

Okinawa Background — Processing the KUNISHI RIDGE with Recoilless Rifles

The final battles on Okinawa saw American soldiers and Marines using tanks and armored flame throwers a small distance ahead of the infantry. The infantry killed any approaching Japanese suicide anti-tank squads and the tanks engaged Japanese cave openings to kill or suppress Japanese infantry for flame thrower tanks and infantry so that they could get close enough to kill or entomb the Japanese.

The Marines histories referred to this as “Processing” the Japanese.

These tactics started to take on a momentum with the exhaustion of Japanese mines and ammunition for crew served heavy weapons.

That didn’t mean the Japanese could not kill if you got careless, as General Buckner’s death proved, but the collapse of organized Japanese resistance was in sight.

In the middle of this, the US Army’s 7th Infantry division was given three to five each 57mm and 75mm recoilless rifles. These weapons were the latest technical advance by US Army Ordnance and they made a great impression on American ground troops using them. The following is from Chapter II-10, VICTORY AND OCCUPATION, the official history of the USMC in WW2.

Nearly two weeks of punishing and brutal fighting were to ensue before the two army divisions could eliminate all enemy resistance in this Thirty-second Army defense sector. (See Map IX, Map Section.) XXIV Corps units spent the period 4-8 June in regrouping and attempting to gain favorable jump-off positions for the attack on the escarpment on the 9th. All supporting arms were employed to soften the well-organized enemy defense system. Armored flamethrower, tank, assault gun, and artillery fires were added to the point-blank blasts of experimental 57mm and 75mm recoilless rifles74 in an effort to reduce the natural bastion.
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and
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74. These newly developed weapons had been sent to Okinawa in late May by the War Department for test firing under combat conditions. After the limited supply of ammunition accompanying the weapons had been expended, air shipments of the special ammunition were rushed to the island in time for employment by XXIV Corps units at the escarpment. Field commanders who had the opportunity to use these weapons were unanimous in their praise and recommended that the recoilless rifle be adopted as a standard infantry weapon. According to the former commander of the 7th Marines, these weapons “. . . could have been used to great advantage by the 7th in its seizure and processing of Kunishi ridge. They were asked for but the reply came back [that] all their ammunition had been used up.” Snedeker ltr 1965.

Update 22 June 2010

This is from the USMC history monograph OKINAWA: Victory in the Pacific. It provides a wider context for the use of the recoiless rifle on Okinawa:

The entire 711th Tank Battalion moved into the 7th Division’s front lines on 10 June as the 17th and 32d Infantry renewed their attack. Under cover of tank guns on the landward side and NGF from the sea, 1/32 made a slow but steady advance onto the eastern slopes of Hill 95, while 2/32 moved through Gushichan toward Hanagusuku as its left flank was gradually uncovered. Armored flame throwers were brought up to burn the enemy out of the jagged coral outcroppings that crowded the crest and sides of the ridge. The 17th Infantry’s forward progress during the day’s attack was limited as the 3d Battalion strengthened its tenuous hold on the escarpment and 1/17 blasted the southeastern face of Yaeju Dake from its positions near Tomui. The division for the first time since the rainy season began was able to employ the full power of its supporting weapons.
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Tanks and artillery also played an important part in the 96th Division’s 700-yard advance on 10 June. A constant drumfire of shells exploded on and against the escarpment, seeking out enemy guns and reserve assembly areas. Under cover of the supporting fire the four assault battalions attempted to cross the open areas at the foot of the slope. In the 383d Infantry zone the 1st and 3d Battalions were able to secure the railroad track that led from Itoman to Iwa before their advance was stopped. Enemy machine guns firing from Yuza Dake and a hill near Yuza just within the 1st Marine Division sector raked both battalions with murderous fire and forced them to dig in. The combined fire of tanks, assault guns, artillery, and experimental 57mm and 75mm recoilless rifles150 was insufficient to silence the enemy opposition, and the 383d was forced to dig in just south of the rail line.
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and
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150. The War Department sent teams of ordnance men to Okinawa to test the combat utility of recoilless rifles. Demonstration firing against enemy caves and pillboxes were conducted late in May, and after air shipments renewed the extremely limited ammunition supply the new weapons were used by both the 7th and 96th Divisions against the Yaeju Dake-Yuza Dake Escarpment. The destructive power, accuracy, and portability of the recoilless rifles impressed unit commanders who had the opportunity to use them in action and led to recommendations by both divisions that they be adopted as standard infantry weapons.

End Update.

The US Army’s Sphinx Project and combat tests in Okinawa, Germany, and Luzon had convinced the US Army to:

1) Add six 75mm recoilless rifles to each Infantry Battalion heavy weapons company (replacing three towed and useless in an infantry assault 57mm anti-tank guns),
2) Add three 57mm recoilless rifles to each infantry company’s heavy weapons platoon, and
3) Create and add a Bazooka/Flame thrower squad to each line infantry platoon,

as a part of the “R-table” infantry divisions it intended to field for the invasion of Japan.

The weapons and the men for these organizational changes were to be provided to MacArthur between Okinawa and the Operation Olympic.

Not all units in the landings would get the recoilless rifles — the USMC “G-table” division organization it intended to use for Olympic didn’t have any of these weapons. Nor was it likely that all 6th Army infantry regiments would be reorganized by the time of the landings. However, it is certain that the useless for fighting cave fortifications 57mm anti-tank guns would be left behind in favor of more infantry with bazooka’s and flame throwers if the recoiless rifles were not available.

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15 June 1945

On Okinawa, Marines suffer heavy casualties and are unable to advance on Kunishi Ridge. The US 1st Division, already short of troops, is attached to the US 2nd Marine Division.

Forces of the US 24th Corps continue operations to eliminate Japanese positions on Mount Yaeju and Mount Yuza.

Landing Vehicle Tracked (LVT) on 01 April 1945

Okinawa Campaign Background -- LVT Attrition

The USMC, at the beginning of the Okinawa campaign, had used previous island assaults as the base line for provisioning spares and supports for it’s landing vehicle tracked (LVT).

It was utterly inadequate in the face of the reality of protracted combat on Okinawa:

At the beginning of the campaign, the 4th and 9th Amphibian Tractor Battalions with a total of 205 LVTs were attached to the 6th Marine Division. Added to those in the 1st and 8th Battalions attached to the 1st Marine Division, the total number of LVTs available to IIIAC was 421. IIIAC AR, chap VII, p. 101. The resupply of spare parts for LVTs was totally inadequate, especially in the case of such vitally needed basic items as tracks, track suspension system parts, front drive assemblies, and transmission parts. The lack of all of these deadlined a good many LVTs and severely limited the amount of support they could have provided during the drive to the south and in the Oroku landing. At the end of the campaign, 75 LVTs had been completely destroyed as a result of enemy action, or, having been badly damaged, they were cannibalized for spare parts. Of the 346 vehicles remaining, 200 were deadlined for lack of spare parts. Ibid., p. 102.

There were 421 LVT-3 and LVT-4 on 1 April 1945. By the end of the campaign only 146 of that 421 were operational. A number a hair under 35% of the original starting force.

The logistical implications of those numbers for Operation Olympic in November/December 1945 were daunting.

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12 June 1945

On Okinawa, many of the Japanese naval infantry cut off in the Oruku peninsula, reduced to a pocket of about 1000 square yards, begin to commit mass suicide to avoid surrender.

The US 1st Marine Division captures the west end of Kunishi Ridge during a night attack.

The US 96th Division attacks Japanese positions around Mount Yuza and Mount Yaeju.

13 June 1945

On Okinawa, the Japanese resistance in the Oruku peninsula ends. The US 6th Marine Division records a record 169 Japanese prisoners as well as finding about 200 dead. (This is a large total when compared with previous numbers of Japanese prisoners reported.)

The fighting continues to the southeast, especially in the Kunishi Ridge area where a regiment of the US 1st Marine Division suffers heavy casualties.

The US 24th Corps uses armored flamethrowers in the elimination of the Japanese held fortified caves on Mount Yuza and Mount Yaeju and on Hills 153 and 115.

Battle line on the Kiyan Peninsula, 10-19 June 1945

14 June 1945

On Okinawa, mopping up operations proceed on the Oroku peninsula.

The troops of the US 3rd Amphibious Corps and the US 24th Corps continue to eliminate fortified caves held by Japanese forces on Kunishi Ridge and on Mount Yuza and Mount Yaegu.

An American regiment of the US 96th Division reaches the summit of Mount Yaegu, while the US 7th Division extends its control of Hills 153 and 115.

Okinawa Campaign Background — Goodbye General Mud

The predominant factor in Okinawa fighting for the last few weeks has been rain and mud. Mud so thick and deep that neither tanks nor trucks could move and Okinawan road beds collapsed into sink holes under the weight of the traffic.

Army and Marine LVT and DUKW amphibious vehicles were traveling by water as far as from Hagushi beach to deliver supplies to forward troops. The USMC started using Avenger TBM torpedo bombers to air drop supplies to forward marine units.

Starting the first week of June, the rains abated and by June 10th, Army and USMC M4 Shermans could again get into action at forward positions and supplies could flow by vehicle.

This helped the advance, but as long as the Japanese had heavy weapons to resist with, and the will to use them, they could inflict more casualties, as this passage from the USMC historical monograph “Okinawa: Victory in the Pacific” put it:

Operations of 14 June marked the completion of the Battle for Oroku:
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The ten day battle was a bitter one from its inception to the destruction of the last organized resistance. The enemy had taken full advantage of the terrain which adapted itself extraordinarily well to a deliberate defense in depth. The rugged coral outcroppings and the many small precipitous hills had obviously been organized for defense over a long period of time. Cave and tunnel systems of a most elaborate nature had been cut into each terrain feature of importance, and heavy weapons were sited for defense against attack from any direction.
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Despite the powerful converging attacks of three regiments, the advance was slow, laborious, and bitterly opposed. The capture of each defensive locality was a problem in itself, involving carefully thought out planning and painstaking execution. During ten days fighting almost 5,000 Japs were killed and nearly 200 taken prisoner. Thirty of our tanks were disabled, many by mines. One tank was destroyed by two direct hits from an 8″ naval gun fired at point blank range. Finally, 1,608 Marines were killed or wounded.78

But after Oroku, the Japanese were running out of the mines and heavy weapons they needed to fight the Sherman tanks.

The final act was at hand.

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08 June 1945

On Okinawa, in the north heavy fighting continues on the Oroku peninsula.

In the south, the US 24th Corps prepares to attack Mount Yaeju.

09 June 1945

On Okinawa, the Japanese forces defending the Oroku peninsula are cut off and surrounded by forces of the US 6th Marine Division.

The US 1st Marine Division advance southward to Kunishi Ridge, one of the last Japanese strong points.

10 June 1945

On Okinawa, fighting continues on the Oroku Peninsula, where the forces of the US 6th Marine Division have reduced the Japanese pocket to about 2000 square yards. Heavy Japanese losses are recorded in nighttime counterattacks.

Meanwhile, on the south of the island, the US 1st Marine Division suffers heavy losses in the successful capture of a hill west of the town of Yuza.

The US 24th Corps forces, to the left, launches a major offensive against the last Japanese defensive line, the Yaeju-Dake Line. Japanese resistance is evidently weakening.

YAEJU-DAKE was brought under American artillery fire shortly before the infantry attempted its first advance to the escarpment. Burst at upper left is white phosphorus.

11 June 1945

On Okinawa, the Japanese pocket in the Oroku Peninsula has been reduce to perimeter measurable in yards but their resistance remains fanatical.

An assault by the US 1st Marine Division (US 3rd Amphibious Corps) fails to capture Kunishi Ridge.

A regiment of the US 96th Division reaches the town of Yuza but is forced to withdraw by intensive Japanese fire.

An important height east of Mount Yaeju is capture by American forces.

Okinawa Campaign Background — Colonel Unmacht’s Flame Thowing Fire Hose

June 10th 1945 saw the combat debute of one more flame throwing innovation from Colonel Unmacht’s flame throwing team on Hawaii — The Fire Hose Flame Thrower.

Each of the three M4 Sherman “POA-CWS- “75″ – H1″ companies in the 713th Provisional Flame Thrower battalion were equipped with 200 feet of rubber lined US Navy fire hoses that had been modified to run off the napalm pumps connected to the 290 gallon napalm tank in each Sherman. At the end of these fire hoses was a M2-2 flame thrower assembly that allowed the pumped napalm to be ignited.

In the first action with this device, five Shermans were driven to the base of a cliff and several hundred feet of hose were connected to allow reverse slope Japanese cave positions to be treated with flame. All five Shermans were exhausted of fuel by the end of this action and many Japanese soldiers were killed either by flame or by gunfire as they fled death by napalm.

This innovation was requested based on combat reports and feedback from the Sept-Oct 1944 assault on Peleliu using flame throwing Marine LVT4. The large vehicle mounted flame throwers were very useful, but could not reach many Japanese cave or pillbox positions just out of range in rough terrain.

The fire hose extention solved this problem, and Okinawa is where this innovation was first used.

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07 June 1945

On Okinawa, in the Oroku peninsula, Japanese forces hold attacks by the US 6th Marine Division while the US 1st Marine Division advances southward and isolates the peninsula defenders.

The US 24th Corps is engaged in artillery bombardments.

Okinawa Background — Colonel Unmacht’s 4.2 inch Mortar Gunboats

LVT amphibious tractors move past LCI(M)-809 (center), bound for the Okinawa landing beaches, 1 April 1945.

The redoubtable Colonel Unmacht of Hawaiian flame throwing tank fame was also responsible for another major innovation in off-shore fire support in WW2 — the 4.2 inch Mortar Gunboat.

They were simply LCVP, LSM and LCI landing craft given one to four 4.2 inch (107mm) mortars to provide fire support for landings. The inability of naval gunfire to hit reverse slopes and the short 1,200 yard range of naval 4.5 inch and 5 inch rockets means that the 3,500-4,500 yard range 4.2 inch mortar was ideal to hit the backs of hills and mountains fronting landing beaches.

This is the time line of 4.2 inch gunboat development which supported not only the Central Pacific, but also General Mac Arthur’s SWPA command and the invasion of Sicily!

1942 – Developing doctrine and experimenting
July 1943 – Sicily
Spring 1944 – Saipan, Marianas Group – aborted operation
21 June 1944 – Bougainville, first successful amphibious combat operation
August 1944 – Training in Empress Augusta Bay, Bougainville, Solomon Islands
15 September 1944 – Peleliu, Palau Islands: first LCI(M) combat use
20 October 1944 – Leyte, Philippine Islands
9 January 1945 – Luzon, Philippine Islands
19 February 1945 – Iwo Jima, Bonin Islands, northwest Pacific basin
1 April 1945 – Okinawa, the Ryukyus Islands, northwest Pacific basin

The predominant Mortar gunboats in the Pacific were the LCI(M) followed by the LSM(R) .

This was the performance of the 4.2 inch Mortar Gunboats at Okinawa:

1 April 1945 – Okinawa, the Ryukyus Islands, northwest Pacific basin
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Almost due west and slightly north of Iwo Jima, even closer to the Japanese home island of Kyushu, lies Okinawa. Large scale use of suicide (Kamikaze = Divine Wind) aircraft and torpedo boats were employed against the landing and support forces. Resistance on shore was increasingly determined and suicidal, a harbinger of what to expect in the already scheduled Operations: Coronet against Kyushu, and Olympic against Honshu (the main island).
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CWS-trained Navy crewmen manned a total of 60 LCI(M)s 180 4.2″ mortars in support of Tenth Army in the Ryukyus Campaign. Six days before the main assault of Okinawa , two 6-boat mortar groups (36 4.2″ mortars) supported the diversionary effort against Keramo Retto made by the 77th (New York Statue of Liberty) Infantry Division. On 1 April 1945, the XXIV Army Corps and the III Amphibious Corps successfully carried out the main landings on the western coast of Okinawa. Prior to H-hour on that morning, seven groups of LCI(M)s, each comprised of six boats (7 x 6 x 3 = 126 4.2″ mortars) lined up parallel to the beach behind the assault troops. Each LCI(M) carried 1,000 rounds of HE and 200 rounds of WP. Using Plan Baker, the 42 boats moved through a calm sea at about one knot, their 126 mortars opening up at a point 1,600 yards from shore at a rate of 10 rounds per gun per minute. Firing over the heads of advancing troops, the mortars, in less than an hour, placed about 28,000 rounds on a beach area 1,000 feet deep and 5« miles wide. The mortar boats themselves received no enemy fire.
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Another group of LCI(M)s supported the 2nd Marine Division’s L-Day feint against the southeast coast of Okinawa. Subsequent 77th Division landings at Ie Shima (where the famous WWII correspondent Ernie Pyle was killed) on 16 April received the support of two groups of mortar boats, while three days later a single group fired for the ruse landing made by the same division in southern Okinawa. From 7 May until 27 June, LCI(M)s, in support of Army and Marine troops, shelled the city of Naha and enemy installations in the vicinity of the capital.
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The amphibious use of the 4.2-inch mortar was one of the major contributions of the CWS to the Pacific war. The mortar boat proved extremely effective for close support just before, during and immediately after amphibious landings. It was then that the assault troops, running the gauntlet of enemy fire while attempting to secure a foothold on the beach, benefited from all the support fire that could be provided. The effectiveness of the mortars in this support is best reflected in the steady increase in the number of mortar boats committed to Pacific assault operations. Only four LCI(M)s saw action in the Palau fighting in September 1944. Seven months later a total of sixty supported Tenth Army operations in the Ryukyus. [Vol. III, pp. 532-33]

For the canceled invasion of Japan, there would be over 100 4.2 inch Mortar Gunboats to bombard the beaches of Kyushu. Not bad for a weapon whose primary purpose was to deliver lethal war gases and which didn’t even have a high explosive shell on Dec 7th 1941!

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05 June 1945

On Okinawa, Japanese forces on the Oroku peninsula strongly resist the US 6th Marine Division which nonetheless captures most of the airfield.

In the south the forces of the US 24th Corps near the last Japanese defensive line, running from Yuza in the west to Guschichan on the east coast and based on the three hills, Yaeju, Yuza and Mezado.

Oroku and Yaeju-Dake, 4-11 June 1945

At sea, a sudden typhoon damages 4 battleships, 8 aircraft carriers, 7 cruisers, 14 destroyers, 2 tankers, and and ammunition transport ship, of the US 3rd Fleet.

Two Japanese Kamikaze attacks cripples both the WW1 era battleship USS Mississippi and the heavy cruiser USS Louisville.

06 June 1945

On Okinawa, elements of the US 6th Marine Division advance in the Oruka Peninsula following their landing. Naha airfield is secured.

Elements of the US 96th Division (US 24th Corps) reach the lower slopes of Mount Yaeju and are halted by intensive Japanese fire.

Okinawa Background — The T-6 Ritchie Device

The “Ritchie” T-6 through T-8 series pontoon flotation devices were one of those “could have been” technical marvels of the Western Allies that never quite came off because the Japanese surrendered first.

The US Army Ordnance department developed these kits to make the M4 Sherman medium tank (T-6 type, standardized later as the M19), M24 Chaffee light tank, M18 Hellcat Tank Destroyer (both T-7, later standardized for the M24 as the M20), and M26 Pershing heavy tanks (T-8, canceled in prototype stage in 1946) into amphibious fighting vehicles. It did this by adding ridged, compartment-ed, foam filled floats to the front back, and for the M4 & M26, the sides of the tanks. This made the floats resistant to flooding due to small arms fire damage and the tanks were free to fire their main guns. The kit equipped vehicles were propelled through the water by cup like end pin connectors on their tracks that pulled them forward through the water. The front and rear floats could be blown off by exploding bolts on the landing beach. This made these tank-kits very sea worthy and at Okinawa one LST dropped several Marine T-6 equipped tanks 10 miles off shore at Okinawa and they made it to the beach!

There were several significant down sides to the Ritche kits. First, it took 20,000 man hours per tank to properly water proof the tanks involved, place fording kits, install the floats, add bilge pumps, and then install the track swimming cups. Second, the swimming cups left no “reverse gear” in case the tank had to change course. Third, the float’s exploding bolts threw two inch bolts several hundred yards and required drivers to carefully blow the front floats, back up, blow the rear floats, and then maneuver around the floats afterwards. Finally, the front float was so long that it would hang up on a beach or reef that rose too quickly.

The T-6 was demonstrated to General Patton before D-Day, but General Eisenhower’s staff decided in May 1944 in favor of the canvas sided duplex drive “DD-tanks” because the ridged floats on an M4 weighed 15 tons and increased the length of the tank such that two DD-tanks could be shipped for one T-6 equipped Sherman. The results of that decision spoke for themselves on 06 June 1944.

At Okinawa on L-Day, April 1st 1945, 1st & 2nd Platoons, C Company, 1st Marine Tank Btn, 1st Marine Division (six each M4A2) two platoons of Company A, 6th Tank Btn, 6th Marine Division (M4A3) and Company B, 711th Tank Battalion (M4A1), were equipped with T6 pontoon flotation devices AKA “the Ritche Device.”

There were several reasons for this including the fact that second generation Shermans, particularly the M4A3 marks, had grown too heavy for LCM family of landing craft.

The US Army’s 711th Btn tanks were launched from LSMs 500 yards from the beach as part of the 7th Infantry Division’s assault wave. They hit the beach with no problems and were observed in action by naval historian Adm Samuel Elliot Morrison and they were mentioned briefly in the last book of his WW2 Naval history series.

The 6th Marines tanks were similarly successful.

The 1st Marines tanks, as mentioned earlier, were dropped an hour later into the water 10 miles off shore and took five hours to get to the reef off the beach. In the course of their landing, these tanks found most of the problems of the Ritche device. Along the way one of the 1st Marine’s tanks managed to ram a US Navy Destroyer because the tank could not turn fast enough or reverse, and the Destroyer refused to change course. When they reached the beach, they had to be winched over the reef by a bulldozer because the front of the pontoons fouled the steep angle of the reef. When finally on the beach, they ran out of fuel!

At the end of the war in August 1945, there were 500 T-6 kits for M4 Shermans, 250 kits each for the M18 Hellcat and M24 Chaffee. They would undoubtedly have been used during Operation Olympic and provided the Japanese defenders of Kyushu a huge tactical surprise as M4 Shermans crawled out of the surf before the first assault wave of infantry carrying LVTs made it to shore.

The M26′s T-8 float device was not ready for Operation Olympic, but might have been for Operation Coronet in 1946 at accelerated war time development and production rates.

This is what I found on the history of the T-8 Device for the M26 Pershing:

Armored division as an assault landing force
The Armored School.
May 1952.

Pages 73-77

Rigid Flotation Devices. A more rugged type of flotation device for the M4 medium tank, known as the T-6 was employed experimentally by Marine and Army tank units during the Okinawa landing.

This would enable the driver to speed up or slow down either propeller by use of the normal tank steering as is done with all water craft having two propellers.

Here are some more places I have found the history of the Ritchie kits:

http://warriorsaga.com/ This site is the story of Ordnance Sgt and later Captain Floyd Coleman who was on the Ordnance demonstration team for the T-6 Device.

Page 38 of “M24 Chaffee Light Tank 1943-85″ By Steven J. Zaloga, @2003 Osprey publishing limited.

Pages 108 and 109, “US Military Vehicles: World War II,” by E.J. Hoffschmidt and W.H. Tantum,

Pages 280, 281, 282, 319, and 352 of “Marine Tank Battles in the Pacific,” By Oscar E. Gilbert

Pages 97, 98, and 232 of “Marines under armor: the Marine Corps and the armored fighting vehicle, 1916-2000,” By Kenneth W. Estes

Page 265 of “Camp Colt to Desert Storm: the history of U.S. armored forces,” By George F. Hofmann, Donn Albert Starr, mentioned that 45 Marine Sherman’s were fitted with T-6 Flotation devices.

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04 June 1945

On Okinawa, two regiments of US 6th Marine Division make landings on the Oroku peninsula in an attempt to outflank Japanese defensive positions.

The battle line on Oroku Peninsula, 4-13 June 1945

However, this is the base area of the Japanese Navy on Okinawa. The local IJN commander, after at first obeying orders to retreat to the Kiyan line, dislikes his new position. He disobeys orders and has his troops reoccupy their original cave positions at Oroku.

The 32nd Army papers over the mutiny by sending orders after wards approving this action.

BASE OF OROKU PENINSULA, where Okinawa Base Force made its last stand 10 days after the Marine landing.

General Buckner, commanding US 10th Army, reduces the frontage of the US 3rd Amphibious Corps. The Marines have suffered the greatest losses, and the 6th Marine Division is stuck in a dogfight with the entrenched IJN base force on Oroku.

The IJA Kiyan line, 4 June 1945

The frontage for the US 24th Corps’ 7th and 96th Divisions are increased to make up for this.

Okinawa Campaign Background — Fighting the Mud Monster

No amount of words I write can say how bad the mud was at Okinawa the way that the following pictures do:

MUD AND SUPPLY were major problems in pursuing the Japanese southward from Shuri. Success depended largely on ability to move American supplies over bad roads. Tractor (above) is pulling a reconnaissance car uphill from portable bridge in the hollow.

Supply trucks pulled through bad spot by 302d Combat Engineers

When roads became impassable to motor vehicles, horses were used.

1st Division marines resort to hand carrying of supplies and wounded as roads are washed out by torrential rains.

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02 June 1945

On Okinawa, mopping up continues as the US 6th Marine Division prepares to land two regiments on the Oroku peninsula.

The US Army 77th Division and it’s supporting 706th tank battalion are pulled out of the line.

The remainder of the Okinawa campaign will be fought by the 24th Corps 7th and 96th Divisions and the 3rd Amphibious Corps 1st and 6th Marine Divisions.

03 June 1945

On Okinawa, Japanese forces are isolated in the Oroku and Chinen peninsula.

The 7th Division cuts across the base of the Chinen peninsula to the south east coast. It finds the peninsula almost devoid of Japanese troops.

The Ninth Japanese “Floating Chrysanthemum” aerial suicide attack on American navy radar pickets begins.

Okinawa Background — The Engineer Special Brigade

Long time military wargamers — grognards — have long noted that the American military, and the US Army in particular, has always been very good at logistics. In the Cold War this was expressed as “Americans always love a technological solution.” Before the advent of highly technological military aviation, this was better expressed as “Americans always love a material and organizational solutions.”

In World War 2, this habit of institutional excellence was best expressed in the form of the US Army Engineer Special Brigade.

One of the little know facts of WW2 — thanks to post WW2 USMC PR campaigns — was that the US Army did more amphibious landings, did larger amphibious landings (See Normandy), faced tougher on-shore opposition (See German tank division counter attacks on beach heads at Sicily, Salerno and Anzio) and faced worse aerial opposition (Luftwaffe guided bombs in 1943 and the Japanese Kamikazes appeared first, with better pilots, lasting longer in worse geographic conditions in the Philippines at Leyte and Lingayen) than the US Marine Corps. More over, the US Army was better than the Marines when it came to providing supplies across the beach!

This last fact was noted at the time by Admiral Barbey, the commander of General MacArthur’s Amphibious ships who got to see both US Army and USN/USMC Central Pacific logistics-over-the-shore procedures during landings at Leyte. He found that the US Army Engineer Special Brigade troops were much faster than the USN/USMC team at clearing supplies through a beach.

US Navy historian Samuel Elliot Morison also noted this disparate performance in the days following the April 1st “L-Day” landings on Okinawa, that supplies were stacking up on Marine beaches, while Army beaches were running smoothly.

The reason for this at Okinawa was the 1st Engineer Special Brigade. They were veterans of landings in North Africa, Sicily, Italy and Normandy and had been shifted to the Pacific in late 1944 after the Dutch port of Antwerp was captured. They unloaded supplies for the US Army and much gripping by the Marines about superior Army supplies on Okinawa was directly related to them.

This is what wikipedia said about the concept, development and deployment of the ESB’s:

Concept and Development

At the onset of direct American involvement in World War II, it was obvious that the U.S. military would need a large strategic and tactical amphibious capability. In 1941, the United States’ amphibious forces were divided into two corps: one Atlantic; one Pacific. Both amphibious corps were combined Army and Marine Corps commands, administered by the U.S. Navy. The Atlantic Corps consisted of the 1st Infantry Division and the 1st Marine Division, and the Pacific Corps consisted of the 3rd Infantry Division and the 2nd Marine Division. As this set-up quickly proved itself unwieldy, the Joint Staff surprisingly appointed the U.S. Army, and not the Marine Corps, to develop doctrine for sustained amphibious operations. On May 20, 1942, the Army activated its Amphibious Training Command at Camp Edwards, Massachusetts. Subsequently, the Army also activated the Engineer Amphibian Command.
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Initially, the Amphibious Training Command (later, Amphibious Training Center) was tasked to train no fewer than 12 Army divisions (including 1 armored division) in amphibious operations. As the war progressed, the Marine Corps expanded to six divisions and the Army and the Navy began to fight over the procurement and assignment of landing craft and other amphibious assault equipment, resulting in the Army’s decision to ultimately close the Amphibious Training Center. Per its agreement with the Navy, the Army continued to train Engineer Amphibian Brigades, for while the Marine Corps was adept at the initial waves of amphibious assaults, the Marine Corps had yet to create an effective doctrine concerning subsequent support waves. This task fell to the EABs.
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Deployment and Subordinate Units
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The 1st, 5th, and 6th Engineer Special Brigades were assigned to the European Theater of Operations, while the 2nd and 4th Engineer Special Brigades were assigned to the Pacific Theater of Operations. The 3rd Engineer Special Brigade was assigned directly to the Amphibious Training Center; responsible for the training of various Army units in amphibious warfare until the dissolution of the Amphibious Training Center. It was then assigned to the Pacific Theater of Operations. The 1st Engineer Special Brigade was the only ESB to fight in both theaters of the war.
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The various subordinate Engineer Boat, Engineer Amphibian, and Engineer Shore regiments were all redesignated as Engineer Boat Shore Regiments (EBSR) by the end of the war.

The inner-service politics of the ESB’s was torturous and is today little known.

It is, however, very important for understanding the real story that underpinned the strategies of the Pacific War — Logistics:

During June and early July 1942 the Allied situation throughout the world grew more perilous. The Afrika Korps routed the British Eighth Army and reached within striking distance of the Nile; von Bock’s great group of armies started its 1000-mile plunge from Orel to Stalingrad; and the Japanese, despite the naval battles of the Coral Sea and Midway, still threatened Australia.
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To the Combined Chiefs of Staff, meeting in London early in July, the most serious danger appeared to be that the German summer offensive would succeed in knocking Russia out of the War. In order to do what little they could to relieve the pressure on the hard pressed Red armies, they agreed to launch, if necessary, a crosschannel invasion of France, even though the forces at their disposal were pitifully small. To do this they would need more landing craft and crews than were available in the British Isles; so the 1st Brigade on July 23 was ordered to England as fast as it could be moved. The Brigade was in a sad state of confusion, with almost no equipment and all ranks barely oriented as to their technical missions and training objectives. Nevertheless, equipment was rushed from all parts of the country to the Brigade, and it was brought to full strength and sailed from New York on August 5th. Hardly had it debarked in England when it became apparent that the German drive was slowing down in the Caucasus and was being fought to a standstill at Stalingrad, and that it would not be necessary to launch the major attack across the channel during that year. Given this breathing spell, the navies of both Great Britain and the United States set about reversing the decision made in May to have the Army run the small landing craft, and in England they actually took away the 1st Brigade’s boats.
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Back in the United States a bitter wrangle ensued, and the understandably inexpert performance of some of the engineer boatmen in their first maneuvers lent weight to the Navy’s argument that only ‘boys in blue’ could satisfactorily handle boats. Colonel Arthur Trudeau, the Chief of Staff of the Engineer Amphibian Command, made a flying trip to visit General MacArthur in Australia during the early part of October to see if he was interested in continuing the development of the amphibian brigades. Just at this time MacArthur was engaged in his “Battle of the Marne” in the passes of the Owen Stanley Mountains and in the steaming jungles and plantations of Milne Bay. Though he had been successful in driving the Japanese back toward their bases on the northeast coast of New Guinea, lack of water-borne transportation had caused him to rely almost exclusively on his pitifully few airplanes, and he was, necessarily, in a most receptive mood. He promptly informed the War Department that he would like one engineer amphibian brigade immediately, to be followed in 1943 by a second one. The War Department, therefore, reduced the number of brigades to be created by the Engineer Amphibian Command to three.
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Thus, the Navy’s campaign to keep the Army out of the boat business succeeded to the extent that the amphibians in the European theater were henceforth to be nothing more than shore party engineers, while in the portion of the Pacific under Admiral Nimitz’s control there would be no specialized amphibian engineers at all. Only in the Southwest Pacific were the amphibian engineers to be given a chance to operate in the manner originally contemplated in the dark days of May, 1942.

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01 June 1945

On Okinawa, after the fall of Shuri Castle, General Mushijima orders the Japanese troops to withdraw southward, towards the Oroku peninsula and the hills of Yaeju, Yuza and Mezado in the extreme south of the island. There are reports of discontent among the Japanese troops, something previously unheard of in the Imperial Army.

Elements of the US 1st Marine Division cross the Koruba river, south of Naha.

The forces of the US Army 24th Corps pursue the retreating Japanese while elements mop up around Shuri.

Okinawa Campaign Background — The Medium Tank Shortage

Up until this point in the Central Pacific Theater of the Pacific War, the Japanese had only put up scattered 37mm anti-tank guns and 37mm armed Type 95 light light tanks against American M3 Stuart light tanks and M3 Grant and M4 Sherman Medium tanks.

These operations were small in terms of tanks used and taught US Army Central Pacific tank unit commanders some very bad habits in terms of operating without close infantry support. This became apparent with the veteran 193rd Tank Battalion supporting the 27th Division at Kakazu on 19 April 1945. The 193rd lost 22 of 30 tanks engaged along with it’s battalion commander.

There were reasons for this. The first place where the Japanese put in a integrated anti-tank gun based defense doctrine was Iwo Jima — A nearly pure Marine Corp landing operation. The second thing that stood out at both Iwo Jima and Okinawa was that the Japanese made a concerted effort to totally destroy knocked out tanks to prevent their recovery by American forces.

The duration of the operation at Iwo Jima was too short, and the operation too close to Okinawa, for the implications of USMC tank losses to be incorporated in the logistical planning for the US Army dominated 10th Army staff for Okinawa.

This is what the US Army Ordnance Department WW2 green book ON BEACHHEAD AND BATTLEFRONTsaid on the subject of that planning short fall:

CHAPTER XXIV
Crescendo on Okinawa

Heavy Tank Losses
The tanks were having a hard enough time against the withering Japanese fire, especially fire from the 47-mm. antitank gun, which was accurate and deadly. The gun was small and easily concealed and its high muzzle velocity would send a projectile through any part of a medium tank except the glacis plate. At Kakazu on the morning of 19 April in the 27th Division’s sector, Company A of the 193d Tank Battalion lost four tanks from a single 47-mm. piece firing only sixteen shots and later in the day had many more cut down by artillery fire, some of them the scarce and
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[462]
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valued flame throwers. The company returned with only eight out of thirty tanks— the greatest loss suffered by American armor in any single engagement on Okinawa.24
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Six of the tanks lost in this action at Kakazu were destroyed by satchel charges placed by Japanese suicide squads that seemed to spring out of the grass beside the tank, sometimes forcing turret lids open and throwing in grenades that killed the tankers. These squads of three to nine men did not cause as many tank casualties as the 47-mm. gun, but they continued to be a constant source of danger. Each man of the squad had his own job: one would blind the tank with smoke grenades, another would force it to button up by hurling fragmentation grenades, another would immobilize it with a mine under the track. The final act was destruction of the tank and crew by a satchel charge.25
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Against such tactics, Tenth Army Ordnance in Hawaii had devised the backscratcher but just what it accomplished was hard to determine. Only a few were actually mounted on Army tanks, none on Marine tanks. In one case the device wounded rather than killed the attacker; in another, rain shorted the circuit so that the mine did not detonate. The few times the backscratcher appeared to be effective, friendly fire took equal credit for destroying the enemy.26
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The test of the sanded paint applied to the tanks of the 713th Armored Flame Thrower Battalion for protection against magnetic mines was also inconclusive, for the battalion encountered no mines of this type.27 Antitank mines did, however, account for about 31 percent of all tank losses on Okinawa. Luckily there were few antipersonnel mines among them to interfere with tank recovery. The problem in bringing back the tanks was the lack of enough tank recovery vehicles to do an adequate job. Often after a tank was immobilized by a mine, satchel charge, or antitank projectile, or because it had simply thrown a track or bogged down in bad terrain, it was abandoned by its crew, and if not recovered by nightfall it would be demolished at leisure by the returning Japanese.28
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By the end of May, the four Army tank battalions and the one armored flame thrower battalion had suffered 221 tank casualties, not counting Marine losses. Among the 221 tanks put out of action, 94 (including at least 12 of the irreplaceable flame throwers), or

43 percent, had been completely destroyed

. The effort by Tenth Army Ordnance to make up these losses was painfully unproductive. To begin with, losses on such a scale had not been anticipated. In the planning, a small reserve stock of 13 medium tanks was to be placed on Saipan for fast emergency shipment to Okinawa. These were sent for on 25 April. But even this small reserve had not been established on Saipan. The tanks had to be ordered from Oahu and did not arrive at Okinawa until 10 June—
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[463]
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some ten days before the campaign was virtually over. An additional shipment of 65 Shermans and 25 tank recovery vehicles was requested from Oahu on 28 April. They were shipped on 20 May and did not arrive until 15 July—almost two weeks after the campaign had been declared officially at an end.29
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Because of the delay, all serviceable medium tanks were stripped from the 193d Tank Battalion (the unit crippled at Kakazu) and distributed to other tank battalions. By early May the tankers were asking for a tank heavier than the Sherman, with a weapon of higher muzzle velocity and thicker armor plate. The M26 Pershings seemed to be the answer. In mid-May (after V-E Day) twelve were requested from the United States, but they were not received until August. In the meantime, to provide better protection against the 47-mm. gun, the Ordnance tank maintenance companies welded steel track sections to the side sponsors, turret sides, and glacis plate of the Shermans, and also used armor plate from wrecked tanks to reinforce the sponson and shield the suspension system.30
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In the end, however, the best defense for the Sherman turned out to be the infantrymen who accompanied it as part of the tank-infantry team, a truth forcibly brought home to commanders in the catastrophe at Kakazu where the tanks had been operating alone. In the early assault on the Shuri defenses, the Japanese, who knew the value of the infantryman, attempted to pin down the infantry with artillery and mortar fire, often successfully. But as the long bloody battle for Shuri dragged on through April and May, the Tenth Army commanders learned about cave warfare and how to win it. They directed artillery fire on cave entrances, forcing the Japanese gunners back into their tunnels; then infantry and tanks closed in, the infantry protecting the tanks from the suicide squads. Having gained a foothold, the troops could move down on cave openings from above, sealing them with flame or explosives, a method that General Buckner called “blowtorch and corkscrew.”31

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May 30, 1945

On Okinawa, American forces reach Shuri, south of the former Japanese positions. Two battalions of US Marines reach the southeast edge of Naha.

The withdrawal of the 44th independent Mixed Brigade to the Kiyan line, 31 May 1945

May 31, 1945

On Okinawa, the US 6th Marine Division (part of US 3rd Amphibious Corps) encounters Japanese rearguards near Hill 46. Japanese forces pull out of Shuri.

The Shuri Line has fallen!

Final withdrawal of the 62d Division, 30 May thru 4 June 1945

Okinawa Campaign Background

American 10th Army intelligence did not realize this retreat was happening until 30 May and in addition, it did not know where the next line of defense would be. A program of interdictive artillery fire was started, but it did not reach as far south as the Kiyan line.

Heavy rains and mud plus, rear guard Japanese cave pill-boxes, made a rapid American pursuit impossible.

Between May 25th and June 4th 1945, the Japanese 32nd Army lost 20,000 of it’s 50,000 remaining troops retreating to the Kiyan Line.

This compares to the 7,000 the 32nd Army lost in it’s abortive May 4-5th 1945 offensive.

The loss in Japanese combat power was even worse than those raw numbers indicate. Only one in five of the combat troops present on 01 April were still able to fight. The loss of crew served infantry heavy weapons was worse. Only one-fifth of the original machine guns survived. Japanese hand grenades and mines were now almost exhausted.

Only one-tenth of the heavier weapons like 50mm mortars, 37mm and 47mm anti-tank guns, 70mm battalion level infantry support guns and 75mm field artillery survived.

The coming defense of the Kiyan line against American tanks would be compromised, between the shortage of mines and the lack of anti-tank guns. The approaches to and through the Kiyan line were good tank country, and despite killing close to 1/2 the American Sherman tanks in the invasion force, the starting force of Shermans was so large — the two Marine medium tank battalions (45 ea. M4 Sherman), four independent Army medium tank battalions (53 ea. M4 Sherman and 6 ea. M4 (105mm) assault guns) and one armored flame thrower medium tank battalion (54 ea. POA-CWS-H1 Flame thrower Shermans and 3 ea. M4 (105mm) assault guns) — that those left would be unstoppable.

The only bright spot was half of the IJA 5th Artillery Command’s large field guns were still intact, including sixteen 150-mm howitzers, because were kept in the rear with thus were relatively unscathed.

However, since this heavy artillery had only 1,000 rounds of ammunition per gun at the start of the campaign. Their remaining combat power was as limited as their ammunition.

According to Leavenworth Papers Number 18, Thomas M. Huber’s Japan’s Battle of Okinawa, April-June 1945

The Japanese withdrawal to fresh lines in the south succeeded in part because the Americans did not make an early concerted effort to break through the Shuri shell. On 26 May American aerial observers noted men, artillery, and armor moving south, but they also reported a large column moving north. This latter force was probably the IJA rear-area garrison units that were called up from the Chinen Peninsula to aid in the 25-26 May attacks on Yonabaru. Since the American analysts were not aware of an overall pattern of southerly movement, they concluded that the Japanese were using the bad weather to cover an overdue rotation of reserve and frontline troops.43
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Visibility on 29 May was zero, and air observation was impossible. Nevertheless, by 30 May, because of vacated IJA positions found west of Shuri and other accumulating bits of evidence, U.S. Tenth Army intelligence finally reached a consensus that the Shuri lines were being abandoned. But the Americans did not know where the new lines were and assumed they were about two miles behind the old ones, just enough to straighten out the salients the Americans had built up on the east and west .44
U.S. Convoy
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American forces elbowed into Shuri on 31 May, completing the reduction of the formidable Shuri line. They realized by this time that they were dealing only with a rear guard. The American force prepared to pursue the Japanese southward on 1 June, but by this time, the 44th IMB, the last IJA unit in the vicinity, had already completed its withdrawal. Moreover, given the sheltered nature of the Japanese defenses, it was impossible for the Americans to move forward safely if even a few Japanese remained in the pillbox caves. Those last few had to be eliminated, and that inevitably took days. The problem remained even after the Shuri line fell, because the IJA 62d Division and the 24th Division’s rear guard both manned intermediate positions between Shuri and the Kiyan area. Even though the IJA screening forces were few, safe and rapid forward pursuit by the Americans was impossible. In the upshot, U.S. Tenth Army units were not aligned and ready to engage the new Kiyan lines until 6 June.45

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The Abandonment of the Shuri Line

May 21, 1945

On Okinawa, US 3rd Amphibious Corps reports advances near the Horseshoe, Half Moon and Wana positions, on the western flank.

On the east-side, US 7th and 96th Divisions (parts of US 24th Corps) attack near Yonabaru.

Japanese forces begin to pull out of the Shuri Line.

May 22, 1945

On Okinawa, American forces enter Yonabaru and capture Conical Hill. Heavy rains begin that hamper offensive operations for the coming weeks.

The positions on the left and right of the Shuri line are about to fall leaving the main defensive positions flanked. The Chiefs of staff of the 32nd Army’s main combat units hold a meeting that will determine the remainder of the Okinawa Campaign. The three options they discuss are:

1) Encircle Shuri Castle and prepare a concentrated defense with the 50,000 remaining troops and long range guns. This proposal retained most of the Japanese heavy guns and artillery ammunition, but there are not enough cave positions in this area to shield all the remaining troops from American artillery.
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2) The second option considered was to withdraw east from the Shuri line to the Chinen Peninsula. This was rejected due to poor roads that would hamper the withdrawal and had the same problem of the lack of cave positions plus a lack of stockpiles of food and ammunition.
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3) The third options was to withdraw south and form a line across the Kiyan Peninsula. This option was chosen because there were enough cave positions with stockpiles of food and small arms ammunition to fall back on.

May 23, 1945

On Okinawa, after occupying Naha, the US 6th Marine Division (part of US 3rd Amphibious Corps) encounters heavy Japanese resistance to attempts to advance further south.

Japanese aircraft begin a three-day series of strikes against the Allied naval forces around the island. This is the seventh kikusui or “Floating Chrysanthemum” suicide strike.

Reverse slope of Warta Ridge, U.S. forces captured this position only 1,000 yards northwest of the Shuri command cave on 21-23 May

May 24, 1945

On Okinawa, during the night, Japanese paratroopers on a suicide mission are landed on American held Yontan airfield.

According to naval historian Samuel Elliott Morrison, four of the five Sally transports are destroyed before landing. The fifth transport lands ten “geritsu” paratroopers who destroy seven aircraft, damage 26 others and blow up a fuel dump with 70,000 gallons of aviation gasoline before being wiped out.

Meanwhile, Japanese troops conduct vigorous counterattacks in the direction of Yonabaru and make a small penetration into the lines of the US 32nd Division.

May 25, 1945

On Okinawa, the US 4th Marine Regiment eliminates the Japanese casemates and underground positions on Machishi Hill.

The US 29th Regiment secures Naha. The beaches at Naha will soon replace Hagushi beach as the main logistical landing beach for Okinawa operations.

Map 9. Preliminary withdrawal of the IJA 62d Division, 25 May 1945

US Navy Fast Destroyer Transport USS Barry is struck by a Kamikaze and so badly damaged that she is decommissioned and later used as a Kamikaze decoy.

Destroyer USS Storms is struck by a Kamikaze and so badly damaged she is abandoned. Her burning hulk is towed to the smoke screen covered Hagushi beach anchorage, where it capsizes and sinks a few hours later.

US Navy Minesweeper USS Spectacle is struck by a kamikaze at the Kerma Ritto anchorage and is abandoned. The large landing craft LSM-135 that rescues her crew is also struck by a Kamikaze, beaches on a nearby reef, and is abandoned.

May 26, 1945

On Okinawa, American bombers and artillery attack Japanese troops withdrawing from the Shuri Line.

The remnants of the IJA 62nd Division stage a series of night attacks the American 77th Division at Yonabaru.

May 27, 1945

On Okinawa, American forces attacking southward, continue to encounter heavy Japanese resistance.

Japanese aircraft begin a three-day series of strikes against the Allied naval forces around the island. This is the eighth kikusui or “Floating Chrysanthemum” suicide strike.

Battleship USS Mississippi completes the destruction of Shuri Castle. The rubble of the castle is later used to make roads supporting the American advance.

May 28, 1945

More than 100 Japanese planes are shot down near Okinawa.

One American radar picket destroyer, the USS Drexler, is sunk in by a Kamikaze.

Night time Kamikazes attacks under a 50% overcast and a full moon cause damage to several merchant ships and a transport. The Josiah Snelling is struck off Ie Shma and at Nakagusuku Wan the merchantmen Brown Victory and Mary Livermore and the transport Sandoval are hit. None of these ships are seriously damaged.

May 29, 1945

The IJA 62nd Division attack American positions at Yonabaru on the night of 25-26 May convinced American commanders that the Japanese intend to defend existing lines. This allows the IJA 24th Division to be pulled back from the northeast part of the line to the southwest on 29 May (see map 10 below) in a “zero visibility” driving rain storm that grounds all American aircraft surveillance.

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Sunday May 20, 1945

On Okinawa, American troops secure Chocolate Drop Hill after fighting in the interconnecting tunnels.

Elements of the 1st Marine Division, part of US 3rd Amphibious Corps, capture Wana Ridge.

Elements of the US 6th Marine Division, part of the same corps, begin mopping up operations in the Japanese held caves of the Horseshoe and Half Moon positions. They use flame-throwers and hollow-charge weapons and seal off some Japanese troops.

Japanese forces counterattack on the Horseshoe position suffering an estimated 200 killed.

To the east, the US 7th and 96th Divisions, of US 24th Corps, continue to be engaged in the capture of Yonabaru.

Okinawa Campaign Background — Shuri Line Threatened!

The American 10th Army is into the tenth day of an offensive it resumed on 11 May 1945. The unrelenting American pressure of the “Blowtorch & Corkscrew” tank-infantry assaults has pushed the Japanese back close to 1/2 mile on the Shuri line over all and the Japanese are threatened with being flanked, if Yonabaru falls on the Okinawan East Coast.

The failed Japanese general counter offensive by the on 4-5 May 1945 — where the 32nd Army lost 7,000 men out of it’s original 76,000, — has left the 32nd Army’s commander General Ushijima in a crisis and without reserves of troops and artillery ammunition to address it.

American 10th Army intelligence is unaware of this development.