At the beginning of August 1945, few people would have predicted that World War II would be over within a month. Even the small number of Americans who were aware of the Manhattan Project — the secret wartime program to build atomic weapons — could not be sure that the two bombs it had so far produced would end the conflict. Indeed, even as the final preparations were made for the specially modified B-29 bombers to deliver atomic bombs, the War Department was moving ahead with its plans to invade Japan, a massive campaign known as Operation Downfall.
Had it gone forward, Downfall would have been the largest amphibious operation in history, dwarfing the Normandy and Okinawa landings in every respect. The first stage of Downfall, code named Operation Olympic, would have put 14 divisions onto the southern beaches of Kyushu at the beginning of November 1945, backed by an aerial armada that included aircraft from 42 carriers and hundreds of land-based planes flying from Okinawa. At least 450 major warships would be on hand to provide anti-aircraft and surface gunfire support to shield the fleet from waves of kamikaze air and naval attacks. Some 800,000 military personnel, some of them recently transferred from the European theater, would participate in Olympic. The goal of the operation was to seize the lowlands of Kyushu so the allies would have an air base and staging area at the southern end of the Japanese island chain before the next phase got underway.
The second part of Downfall, Operation Coronet, called for 25 divisions to conduct an amphibious assault against the main island of Honshu, landing on the plains southeast of Tokyo. Another 12 divisions would join the fight as the Allied salient expanded. If necessary, the United States would feed another four divisions into the fight each month, most of them veteran units from the war against Nazi Germany.
It was hoped that the capture of Tokyo might finally compel the Japanese government to surrender, but there were no guarantees. Japan still occupied a vast portion of China and could prolong the fight even if the Soviets invaded from the north. In worst-case scenarios, the war might last well into 1947 and cost the United States between 1.7 to 4 million casualties, including some 400,000 to 800,000 dead. Up to 10 million Japanese would become fatalities, and tens of millions more would become sick and starving refugees.
The decision to use the atomic bombs remains controversial. What we can say with near certainty, however, is that an invasion of Japan would have been catastrophic for both sides; we can all be glad Operation Downfall remains a historic footnote.
What will also forever remain conjecture is how those enormous American fatalities would have altered our nation’s history and that of the world. Long Island would look profoundly different. Many families would never have been started, the reinvention of our postwar American economy would have been severely stunted, and the Marshall Plan that put a battered Western Europe back on its feet and prevented the ascendancy of Communism throughout Europe would have been unaffordable. Japan’s strategy of bleeding the victors dry could have been successful, compelling President Truman to accept Tokyo’s conditional terms.
In the end, the iconic images of General Douglas MacArthur conducting the surrender ceremonies aboard the battleship USS Missouri on Sept. 2, 1945 is how the conflict ended. But it could have ended very differently on the beaches of Imperial Japan.
Erik B. Villard is a military historian and adviser to the Museum of American Armor in Old Bethpage.