Battle of Okinawa 65 Years ago today — May 18, 1945

May 18, 1945

On Okinawa, the US 6th Marine Division, part of US 3rd Amphibious Corps, captures most of the Sugar Loaf Hill, as well as parts of the Half Moon and the Horseshoe positions that overlook it, after several days of bitter fighting.

The US 1st Marine Division continues to battle for the Wana river valley and Wana Ridge but fails to eliminate Japanese resistance, even with flame-throwers and tanks in support.

Meanwhile, the US 77th and 96th Divisions, parts of US 24th Corps, attack Japanese positions on Flat Peak without success.

Okinawa Campaign Background — Logistics and Priority Shipments

One of the important things that seems to elude modern historians about the Pacific War is what is now referred to as “Supply Chain Management” by civilian businesses and logistics by the Military. This lack of understanding leaves many Diplomatic and Military histories of the decision to use the Atomic Bomb fundimentally flawed.

In both civilian supply chain management and military logistics you have the run of the mill product and supply flow and you have priority shipments of certain items of critical nature that operate outside that normal system with dedicated transport. Federal Express made a huge business filling that supply chain niche. The USAF’s Air Mobility Command does much the same thing today for the American military with some of its flights.

However, this system of priority shipments with dedicated fast transport is nothing new. It was used often at Okinawa.

Okinawa, like many pacific islands was surrounded by a coral reef. In the era before inter modal cargo containers, roll-on roll-off freighters and container ports, that reef required ships to unload break bulk supplies and troops into landing craft. These landing craft would go to the coral reef and transship supplies and men to tracked LVT and wheeled DUKW amphibious vehicles to be unloaded at on-shore supply depots.

This slow multi-load and unload system meant ships were stuck as floating cargo for extended periods and normal transport turn around became extremely slow.

As a result, several times during the Okinawa campaign there were shortages of mortar ammunition, artillery ammunition, fuel and huge losses of tanks and other vehicles that were unaccounted for in the original invasion plan. This required a “Fed-Ex” style priority air and sea shipment program to support combat there.

From OKINAWA: THE LAST BATTLE pages 410 and 411

About the middle of April a critical shortage of 155-mm. ammunition developed, and on 17 April Tenth Army had to call up four LST’s loaded only with ammunition for 155-mm. guns and howitzers from the reserves in the Marianas. Subsequently, additional emergency requisitions on the reserves were necessary. CINCPOA was also requested to divert ammunition resupply shipments from canceled operations, as well as some originally intended for the European Theater of Operations, to Okinawa in order to alleviate the shortages. On 21 May Tenth Army had to request an emergency air shipment of 50,000 rounds of 81-mm. mortar ammunition, of which more than 26,000 rounds were received between 28 May and 9 June.

and

Shortages of 4.2-inch chemical mortar ammunition, resulting in large part from an unusual percentage of defective fuses, were overcome by the use of surplus Navy stocks and by air shipments of replacement fuses.

The supply of aviation gas on the island always bordered on the critical. Although no air mission’s had to be canceled, generally the two airfields barely had enough gas to carry out all scheduled missions. The relative scarcity of aviation gas was due principally to slow unloading and the lack of bulk storage facilities ashore. Gas tanks were not completed until the end of April; until then gas had to be brought ashore in drums and cans-a slow, laborious process. The use of DUKW’s to take gas directly from the ships to the fields materially expedited unloading. Reserves on hand, however, were never plentiful, and, when a tanker failed to arrive on schedule at the end of April, Tenth Army had to call on the Navy to supply the gas for land-based aircraft from fleet tankers.

and

The loss of light and medium tanks during the campaign, much heavier than had been expected, caused another critical shortage and replacements could not be secured in time. Tenth Army reported the complete loss of 147 medium tanks and light tanks by 30 June; replacements were requested from Oahu on 28 April but these had not arrived by the end of the campaign. As an emergency measure, all the medium tanks of the 193d Tank Battalion, attached to the 27th Division, were distributed to the other tank battalions on the island. XXIV Corps tank units received fifty of these tanks which contributed materially to combat effectiveness. The 193d, however, could not be reequipped and returned to combat.

Many academic historians in the post-World War II era contend that claims by the Chemical Warfare Service and post war US Army Cemical Corps — that priority shipments would support large scale chemical warfare against Japan — were wrong.

They often specifically point to the failure to have enough tanks resupplied to Okinawa during the fighting as the reason why mass chemical warfare was logistically impossible. For example, the turnaround between a 10th Army request to Oahu, Hawaii on 28 April 1945 and replacement tank delivery was 55 days (21 June 1945).

A closer analysis of this claim by academic historians shows this was not the case.

I stumbled across this fact reading M26/M46 Pershing Tank 1943-53 by Tony Bryan, Jim Laurier, and Steven Zaloga, Osprey Publisher New Vanguard 35 Copyright 2000. Page 16 of that book shows M26 Pershings arrived on Okinawa July 21, 1945 with a picture of their debarkation from LCT — landing craft, tank.

There were no M26 Pershings on Hawaii in April 1945.

They had to be delivered by train from American factories to a west coast port of embarkation. Then get delivered to the port of Hawaii, which was the only one in the Pacific with cranes capable of unloading a Pershing from a fast (15 knot) merchant ship. Then get those tanks loaded in the same six knot LCT round-trip-from-Okinawa-to-Hawaii-and-back logistics convoy as 10th Army’s replacement Sherman tanks.

Also, the 10th Army also asked for the canal defense lights as soon as they knew they existed from the US Army Ordnance Department. The CDL was a M3 Grant tank that had a turret mounted search light in place of the standard 37mm cannon and a hull mounted 75m gun. The 10th Army needed them to combat Japanese night infiltration attacks. According to R.P. Hunnicutt in his book Sherman: A History of the American Medium Tank the American supply system delivered 18 CDL tanks to Okinawa between late-June 1945 and VJ-Day on Sept 02, 1945 from Depots in England. That means 90 to 120ish days after a supply request. More likely it is the latter than the former.

Twelve 45-ton M26 Pershing tanks or eighteen 30-ton M3 Grant CDL tanks (officially, T-10 “Shop Tractors”) represents roughly the cargo capacity of a single WW2 fast merchantman.

The ability of fast merchant ships operating outside of convoys from 1) Europe and the West Coast to get to Hawaii, or to go from 2) England to the American East Coast, then ship by train to the West Coast and then by ship again to Hawaii, means some really big things in terms of American 1945 priority logistical capability.

No stopping to form convoys in the Atlantic, Indian Ocean and South Pacific means a huge effective increase in Allied shipping capacity post VE-Day, especially for faster long distance priority shipping.

The historical performance of the American World War II priority shipping system at Okinawa shows the academic historians were wrong. The US Army Chemical Warfare Service (and post-war Chemical Corps) position on chemical warfare logistics against Japan was much better grounded in the operational facts of World War II.

There is a history major masters thesus or PHD in vetting the historical record of Pacific War American military priority shipments with modern supply chain spread sheet data analysis.

Assuming you could find an acedemic institution, and a history department dean, willing to go there.