Olympic would be the largest amphibious invasion ever attempted in military history. Nine divisions in three corps would assault three separate landing areas simultaneously. They would be backed up by five other divisions and at least one independently operating regimental combat team. Three of the divisions in the initial assault were marines, while the rest were army.
The numbers for the navy were even more staggering. Halsey's Third Fleet contained fourteen large carriers and six light carriers, along with nine new battleships, twenty-six cruisers, and seventy-five destroyers. Halsey was to attack targets inland.
Spruance's Fifth Fleet was even larger, with scores of escort carriers and more than four hundred cruisers and destroyers. Spruance was charged with protecting the amphibious force, which counted the almost fourteen hundred ships that would carry more than half a million men to battle.
The island of Kyushu had been chosen because it contained reasonably satisfactory landing areas, two magnificent deepwater anchorages, airfields, and, most important, was within range of land-based air cover from Okinawa and Saipan. This latter point was critical. Without land-based cover, the invasion would be dependent on carrier planes, whose operations were limited and could be shut down by the weather and were vulnerable to Japanese kamikaze attacks.
Despite its gigantic size, the Olympic part of Downfall had specific goals and only called for the conquest of the lower third of the island. Kyushu was about twice the size of Massachusetts and roughly divided in two by mountains that separated the north from the south. The army believed that the Japanese could be driven from the southern part and contained in the north while the south was developed as a base for staging and supporting Coronet.
November first had been chosen because it represented both the amount of lead time necessary to develop and launch the attack as well as being after the end of the annual typhoon season. Typhoons had savaged the American fleets off Okinawa and elsewhere, and a recurrence could be disastrous for the expedition. One typhoon had ripped through Okinawa in early August and caused a great deal of damage to equipment being gathered for the landings on Kyushu.
All of the units involved in the operation were among those already in the Pacific theater. No divisions would be drawn from Europe for Olympic, although two armored divisions were scheduled for deployment from Europe for Coronet in 1946. There were no appropriate areas for massed tank assaults on Kyushu, although there were such places on the Kanto Plain. The infantry and marine divisions would still have their regular quota of tanks, many of which would have flamethrowers instead of cannon.
On X-Day, the marines would attack the southwestern tip of the island and begin to drive overland across the Satsuma Peninsula toward Kagoshima Bay, which ran north-south and roughly split the southern end of Kyushu in half. The two army corps would land on the east side of Kyushu, and one corps would also drive on toward Kagoshima while the second took Ariake Bay. Ariake was on the southeastern end of the island and, even though it was the smaller of the two anchorages, was itself large enough to hold a large fleet.
Truman was bemused because someone responsible for planning must have been a car buff and had named all the sites and areas accordingly. Thus, the marines' main landing areas were Taxicab and Roadster, while the army would be in Town Car and Station Wagon. Specific beaches were named after particular brands, and it was a little unnerving to see future battlefields named Ford, DeSoto, Buick, and Chrysler, along with many others. Attacks just prior to November first would take place on several smaller islands off Kyushu.
Truman put down the folder. "Casualties and options, gentlemen."
As usual, Marshall answered. "Casualties are impossible to predict, as they are based on several unknowns. First, we don't know how many Japs will be facing us on Kyushu, and second, we don't know how hard or how well they'll fight." He took a deep breath, obviously reluctant to give such an estimate. "We have run several analytical models based on the invasions and campaigns of Leyte, Luzon, Iwo Jima, Okinawa, as well as the latter stages of the European war from Normandy to its conclusion. Right now our best estimate for Olympic alone is two hundred thousand casualties from all causes, combat and noncombat.
Truman shook his head. "And if we have to go forward and attack Tokyo, how many for Operation Coronet?"