INTELLIGENCE FORECASTING FOR THE INVASION OF JAPAN
Previews of Hell
OLYMPIC was a fitting code name for the American invasion of the land of the gods. A massive amphibious assault by nine divisions (six stormed the Normandy beaches) would seize three widely separate landing areas on the southernmost Japanese main island of Kyushu. A tenth would assault offshore islands. More than 400,000 American troops were slated for the assault forces. 1 By the spring of 1945 preparations for the invasion were under way. Simultaneously the Japanese were struggling around the clock to turn Kyushu's beaches into massive killing grounds. The showdown was set for 1 November 1945.
Intelligence forecasts predicted the landings forces would encounter at most ten Japanese divisions throughout all of Kyushu. Planners confidently expected American attackers to outnumber Japanese defenders two or three to one in the southern half of the island. But from early spring to midsummer 1945 the forecast changed dramatically. Intelligence, obtained mainly from reading Japanese military and naval codes, uncovered a Japanese buildup on Kyushu of mind-boggling proportions. By August more than ten Japanese divisions defended southern Kyushu alone. Standard tactics would include widespread suicide attacks on the invasion fleet with everything from kamikazes to human torpedoes.
Countless decrypted messages from the high command in Tokyo underlined Japanese determination to fight to the death against the invaders. Japan's planned defense of Kyushu, unwittingly told to the Allies in