From Tennozan: The Battle of Okinawa and the Atomic Bomb, by George Feifer (Ticknor & Fields, 1992), pp. xi-xii:
The battle was the turning point in modern history. That first operation on Japanese soil—Okinawa was politically part of Japan to which it reverted in 1972—was also the last battle before the start of the atomic age. Without the essential facts, it is impossible to understand the decision, made some six weeks after the campaign ended, to use the atomic bomb.
Although no precise assessment of the rights and wrongs of that decision is likely to be made, the debate deserves to be conducted with evidence as well as emotion. The deep revulsion still provoked by the horrors of Hiroshima and Nagasaki is of course wholly appropriate. But it is difficult to evaluate the destruction of those cities out of context, without the knowledge that Okinawan civilians, not to mention the fighting men of both armies there, endured worse. The best estimate of the dead in the two obliterated cities is around 200,000. The Okinawan campaign killed fewer noncombatants, some 150,000. But the total number of dead, including servicemen, was significantly higher. And conventional explosives on the island caused far greater damage to Okinawan tradition, culture and well-being than the atomic bombs did to the Japanese. Measure by sheer suffering as well as by devastation of national life, the battle of Okinawa was a greater tragedy. And had the war progressed to the Japanese mainland, the next battleground after Okinawa, the damage would have been incomparable.
I mention this at the start not to stake a claim in some ghoulish competition to crown the greatest catastrophe, but to point out that the Okinawan suffering has never been recognized; proportionately far smaller losses to Japan and America always prompted much greater sorrow. This book was conceived as an account of the fighting men’s ordeal that never won rightful gratitude in America. I hope it will convey a hint of the immense exertion, terror, agony and carnage in that battle. But nonmilitary issues that emerged during the course of my research pushed me toward a larger story.
Okinawans’ punishment and suffering continue to this day as a direct result of that conflict, although they, the accommodating, exceptionally peaceful islanders, were among its chief victims then. That was one of the war’s plentiful ironies—or inevitable consequences: the weakest and poorest usually bear the greatest burdens.
Okinawa was the only Japanese prefecture that Hirohito never visited.
Here’s a relevant paragraph from the Wikipedia entry on Purple Hearts.
During World War II, nearly 500,000 Purple Heart medals were manufactured in anticipation of the estimated casualties resulting from the planned Allied invasion of Japan. To the present date, total combined American military casualties of the seventy years following the end of World War II—including the Korean and Vietnam Wars—have not exceeded that number. In 2003, there remained 120,000 Purple Heart medals in stock. The existing surplus allowed combat units in Iraq and Afghanistan to keep Purple Hearts on-hand for immediate award to soldiers wounded in the field.