Surpassing OVERLORD: Logistics & Operation DOWNFALL

In June 1944, all eyes were on Europe as the Allies executed one of the most brilliant landings in France, signaling the beginning of the end for Nazi Germany. However, the end of the war was far from certain in the Pacific. By 1945, preparations had begun for an operation that would dwarf OVERLORD in scale and objective. The operation was known as DOWNFALL.

DOWNFALL consisted of two smaller operations. OLYMPIC was designed to take the southern Japanese home islands of Kyushu and Shikoku in November 1945. CORONET was destined to begin in the Spring of 1946, with the Allies attempting to land and take the Japanese home island of Honshu. As we know, however, these operations never came to pass, and neither did the deaths of the estimated millions of American forces nor the elimination of the Japanese – as Emperor Hirohito assessed in his surrender announcement.

The execution of the CENTERBOARD operations circumvented any need for DOWNFALL. The two CENTERBOARD operations were executed on 6 & 9 AUG 1945, respectively – the dropping of the atomic bomb on the city of Hiroshima on Honshu, and Nagasaki, Kyushu.

Originally, DOWNFALL required the 6th Army to regroup following the Battle of Manilla. The intent was to create a strategic triangle of operations at the foot of the Ryukyu Island chain. This triangle was situated from Formosa, to north of Manilla, to Hainan, China. It was assessed that Allied control of this triangle would allow complete ownership the South China Sea. In turn this would effectively sever Japanese supply lines from the south and would end any chance of Japanese offensive operations across the Pacific Theater. Communications, transportation, logistics, and mobility could be controlled in most of eastern Asia by controlling this region. The Japanese Ninth fleets sea lanes and their communication lines were cut with the U.S. 6th Army’s capture of Manilla.

The flow of U.S. supplies across the Pacific would continue until the formal Japanese surrender on 15 AUG 1945. This included the stockpiling of materiel resources, establishing command centers, docking ports, airfields, depots, and much more. Okinawa was designated the point of launch for most of the amphibious landings, with Nimitz’s Pacific Fleet providing artillery support. DOWNFALL even included diversions on Shikoku, with a Reserve Afloat element situated off the coast of the fourth smallest home island.

Even with the best planning, Allied estimates were that an invasion could create more than a million American casualties, and millions more Japanese casualties. Upon review of defenses on the ground in Kyushu, many analysts said their estimates of losses were too low. It was a sobering moment for the Americans, and one reinforced by many in the Japanese military. Nevertheless, as 2 SEP ticked by a flick of a pen signaled the end to a war that threatened to devour millions more. What’s more, the preparation for such a campaign provides a valuable insight into the nature of logistics in the Pacific Theater.

(Click the image to view larger version)

The map used to depict the situation for DOWNFALL.

Of particular interest are the areas that are highlighted as key “Staging Base” locations. Luzon, Okinawa, and Tinian were used, but Formosa was preferred due its ability to better control Southeast Asian operations and manage logistics flowing into the region.

First and Eighth army were tasked with CORONET, while Sixth Army was tasked with OLYMPIC.

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