Operation Zipper, Sept 9, 1945 — The Other “Invasion That Never Was”

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

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:


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)


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)

12 thoughts on “Operation Zipper, Sept 9, 1945 — The Other “Invasion That Never Was””

  1. Early in my career I worked for a gentleman who entered the war as a US soldier just after the fall of Okinawa. His first combat was to be the invasion of Japan.

    When he and his fellow soldiers first heard the news of the atomic bombs on Hiroshima and Nagasaki, they wept in joy with the feelings that their lives had been saved.

  2. The contemplated land offensives in China would have consumed countless lives, as well.

    You have written about the contemplated invasion of Java.

    There was fighting going on in the Phillipines until the end of the war.

    Every day that went by with the war dragging on cost thousands of lives.

  3. I had read of the experiences of British and American civilians interned in the PI, Malaysia and Sumatra, that they figured they were about two weeks from starving to death when they were liberated. And the Japanese plans to exterminate all POWs anyway were already well underway.

  4. With the numerous books I have read about the Japanese policy on POWS it is a consensus that even at the very top the policy was to execute all POWs before the end of the war.

    if you want to read a couple of chilling accounts of POW life I can’t recommend Unbroken, the true story of Louis Zamperoni – highly enough.

    And the book Ghost Soldiers about the Army Ranger raid on a Japanese POW camp in the Philippines, is chilling. Of the 100,000 or so American POWs on the island at the start of he war (and the fall of Bataan), about 6,000 starving an disease-ridden POWs were left just 3 years later.

    Numerous Japanese commanders around the Pacific had their own policy of executing prisoners.

    Read James Bradley’s followup to Flags of Our Fathers , a book about the fate of 6 American flyers on Chi Chi Jima, a small island 150 miles from Iwo. At the time, it was where all Japanese military communication emanated from the Pacific and the commanders were sure there’d be an invasion like Iwo. (That’s where G.W. Bush Sr was shot down for those interested).

    Rather chilling and inhumane account of the fate of those captured flyers.

  5. I will second the recommendation on Ghost Soldiers. The Japs (as my hero Adm. Halsey called them) were animals.

    “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.” I agree with this completely and it would have caused the elimination of a full generation of Japanese.

  6. Dan – I used to have a neighbor – an old Marine who had seen Tarawa, Saipan (and recalled to Korea) the Chosin Reservoir. I told him he was a fugitive from the law of averages ;-)

    He said that the Japanese were worse than the Nazis and never really held accountable. The top ones yes but that was it – MacArthur needed the co-operation of the Emperor to keep the Japanese in line.

    On the book Ghost Soldiers they made a movie on it ( The Great Raid ) and the opening scene – taken from the book – shows a Japanese unit forcing American POWs – about 100 – into a trench where they then poured gasoline and lit it –

    It was an unforgettable scene.

  7. I think — and that is my purely off-the-cuff feeling, from having read so many accounts of what happened to POWs and civilian internees — is that there were just so many instances of brutality and brutal abuse of POWs and civilian internees alike, that after the war, the Allies only had energy sufficient to go after the worst offenders. The very most brutal, the worst of the worst – was about enough that they had the energy to go after. The minor-league brutes – of whom there were many – small potatoes, relatively speaking. Such is life.
    Although, I do hope that certain Japanese and Japanese-Korean prison-camp guards have never spent a sound night of sleep in the years since. I hope that they have spent every night of every year since, fearing that nemesis will blow open their front door and come barreling in.

  8. Sgt Mom – an interesting facet of the book Unbreakable was that it brought back for me a memory from the Tokyo Summer Olympics – in the 1998 Nagano Winter Olympics – during Zamperini’s Japanese Confinement a lot of the book dealt with this sadist nicknamed “The Bird”

    Right after war he disappeared with a death penalty hanging over his head.

    Long story short after decades the death penalty was rescinded and he came out of hiding.

    So I remember his being interviewed during the 1998 games and he was completely unrepentant. He died a few years ago – of natural causes.

  9. I think — and that is my purely off-the-cuff feeling, from having read so many accounts of what happened to POWs and civilian internees — is that there were just so many instances of brutality and brutal abuse of POWs and civilian internees alike, that after the war, the Allies only had energy sufficient to go after the worst offenders

    The first act by the American government in the Cold War was to cover up the crimes of Emperor Hirohito. Specifically his involvement with chemical and biological weapons development and use in China. This decision was made in October of 1945 when the Truman Administration had General MacArthur shut down prosecutions against Hirohito.

    Maintaining a compliant occupation government in Japan while we reformed that nation was more important than justice for our dead.

    Once that happened, all the Allies started using the various surrendered Japanese military units and leaders to maximum advantage.

    Field Marshal Count Terauchi for one should have been put up against the wall and shot for his involvement with the use of Allied POW labor to build railroads in Thailand. Instead Admiral Lord Mountbatten used him to run Japanese forces for the British in what is now modern day Vietnam.

    Still and all, much as I dislike to admit it, the results with regard to modern Japan speak for themselves.

    The militarist death cult leadership of Japan is gone and the nation is not a military threat to American or West Asian interests.

    Maintaining the institution of the Japanese Emperor was vital to that outcome.

  10. So I remember his being interviewed during the 1998 games and he was completely unrepentant. He died a few years ago – of natural causes.

    Thanks for reminding me why it’s okay to believe in hell.

  11. Another great post on what the war going past August 1945 meant for everyone.

    The Battle of Manila (3 Feb – 3 Mar 1945) is instructive to what would have faced Singapore when ZIPPER was *ahem* unzipped.

    Out of a population of 1 million, about 100,000~ died; or 10%. In addition, the city was pretty much destroyed.

    Singapore’s population in 1947 was given as 938,144~; but I don’t know how much was growth after WWII ended several years prior; nor do I have any statistics on the sizes of the two cities in 1945, but there’s a very good case to be made for Singapore becoming Manila II when ZIPPER is initated.

    As for specific numbers of POWs who were alive in 1945; Wikipedia cites Hirohito and the Making of Modern Japan with the following numbers:

    37,583 Commonwealth/UK
    28,500 Dutch
    14,473 USA
    56 Chinese

    The list is likely incomplete; but it gives you a scope of the scale of mass murder that would have been unleashed if we had invaded Japan.

  12. Ryan,

    Singapore would have been much worse than Manila. Singapore was different because there was no way civilians could run away from their murderers — it’s an island, remember — and the Japanese military controlled the entrance and exits. It would have had far more time to do its killing _unopposed_.

    The Japanese did not start killing Filipino civilians in Manila until the 1st Cavalry Division was in the northern part of the city. Of the 100,000 civilians that were killed in Manila, the “general accepted estimate” was 60,000 were murdered by the Japanese and 40,000 more were killed by either American artillery or cross-fire between the Japanese and American troops.

    MacArthur didn’t allow any air strikes at Manila at all nor artillery for the early part of the battle and American troops did their best not to fire on civilians and protect them when they could.

    The surviving Filipinos surprisingly did not begrudge Americans the use of artillery afterward, because it kept the Japanese from killing even more civilians!

    In Singapore, the Japanese had an island shaped killing jar they controlled the access too, and would have had weeks of time.

    That puts Singapore in the high end death range for the “Rape of Nanking,” not Manila.



    Death toll

    Chang wrote of the death toll estimates given by different sources; Chinese military specialist Liu Fang-chu proposed a figure of 430,000, officials at the Nanjing Massacre Memorial Hall and the procurator of the District Court of Nanjing in 1946 stated at least 300,000 were killed, the International Military Tribunal for the Far East (IMTFE) judges concluded that more than 260,000 people were killed, Japanese historian Fujiwara Akira approximated 200,000, John Rabe, who “never conducted a systematic count and left Nanking in February”, estimated only 50,000 to 60,000, and Japanese author Ikuhiko Hata argued the number killed was between 38,000 and 42,000.[28]

    The book discussed the research of historian Sun Zhaiwei of the Jiangsu Academy of Social Sciences. In a 1990 paper entitled The Nanking Massacre and the Nanking Population, Sun estimated the total number of people killed at 377,400. Using Chinese burial records, he calculated that the number dead exceeded the figure of 227,400. He then added estimates totaling 150,000 given by Japanese imperial army major Ohta Hisao in a confessional report about the Japanese army’s disposal efforts of dead bodies, arriving at the sum of 377,400 dead.[29]

    Chang wrote that there is “compelling evidence” that the Japanese themselves, at the time, believed that the death toll may have been as high as 300,000. She cited a message that Japan’s foreign minister Kōki Hirota relayed to his contacts in Washington, DC in the first month of the massacre on January 17, 1938. The message acknowledged that “not less than three hundred thousand Chinese civilians [were] slaughtered, many cases in cold blood.”[30]

    Nor would mass killings have been limited to Singapore. When Operation Zipper went in, the Japanese in SE Asia would start their mass killings across the theater.

    The mass murder of Dutch internees and Allied POWs in Batavia, Java (Modern day Jakarta, Indonesia) was going to put Japan’s Javanese puppet state army in a very tight spot as they either would be ordered to assist with killing of the interned Dutch and Allied POWs (as well as any fellow “rebel” Javanese civilians) or they would have been forcibly disarmed and killed themselves.

    Knowing the Japanese, they would have acted to disarm their puppets first, after the way the Indian National Army disintegrated in Burma. That disarmament would have gone down ugly, brutal and very uncoordinated with some units of the puppet armed forces scattering, armed, to the countryside to join the other “pro-allied” rebels in the hills. After that, the Japanese would have started killing there…and Java is a small densely populated island too.

    Mac Arthur was highly sensitive to the fate of civilian detainees and allied POWs, given what the Japanese did in Manila in March 1945. General Eichelberger, Mac Arthur’s 8th Army CO, was alerted in April 1945 to prepare a contingency plan to invade Java if the Navy and Army Air Corps won the argument of “Invasion of Japan” versus blockade/bombardment in June 1945.

    Ultra would have told MacArthur all of the goings on in Java and he would have acted — to hell with the Joint Chiefs — and the photos of the dead, white, Dutch civilians in Batavia would have given him political cart blanch after the fact.

    As for with what, General Eichelberger had available in late August 1945 the amphibious shipping and logistics in the Southern Philippines to deploy two regimental combat teams — call it 10,000 men — with a couple of weeks of logistical support, with about five days warning.

    This shipping was a combination of amphibious ships training with Operation Olympic divisions, Adm Barbey’s 7th Fleet transports (primarily LST and LSM landing ships) that were “rolling up” equipment and service troops from New Guinea to the Philippines, and US Army Transportation coastal shipping, including US Army flagged and civilian operated LCT’s convoying with Barbey’s transports.

    The Aussies had about one infantry regiment/brigade’s worth of amphibious in Borneo as well under MacArthur’s command.

    MacArthur also had the 503rd Parachute Infantry Regimental Combat Team sitting in the Central Philippines as a part of his AFPAC reserve deciding what he was going to do with it — as the 11th Airborne Division was already committed to Operation Olympic and at the time (6 Aug – 2 Sept 1945) was being staged to Okinawa in preparation to air-landing in Japan as a part of the OPERATION BLACKLIST surrender/disarmament.

    The 93rd Infantry Division (colored) was not a part of Operation Downfall, but was a part of the 8th Army in the Southern Philippines and was used to accept Japanese surrender in the Celebes east of Borneo.

    Ugly and confused doesn’t begin to cover what this operation — with the 503rd RCT dropping into/near Batavia — would have looked like.

Comments are closed.