The sixtieth anniversary of Hiroshima seems to be shaping up as a subdued affair--though not for any lack of significance. A survey of news editors in 1999 ranked the dropping of the atomic bomb on August 6, 1945, first among the top one hundred stories of the twentieth century. And any thoughtful list of controversies in American history would place it near the top again. It was not always so. In 1945, an overwhelming majority of Americans regarded as a matter of course that the United States had used atomic bombs to end the Pacific war. They further believed that...