Japan 1945: From Operation Downfall to Hiroshima and Nagasaki by Clayton K.S. Chun is another excellent book in Osprey’s “Campaign” Series.  Chun examines the final campaigns of World War II in the Pacific as the Allies rolled back the Japanese. Chun also looks at of Operation Downfall (the planned invasion of the Japanese home islands).  Chun explains why Hiroshima and Nagasaki were bombed rather than implementing Operation Downfall.
Chun does an excellent job of summarizing a very complex network of decisions made by President Harry Truman and the Allied military leaders. In addition to the immense casualties that the Allies could incur in an invasion, the Americans and their British allies were wary of Soviet intentions with regards to the occupation of Japanese territory – there were already strains in American/British relations with the Soviets in Europe.
The book is beautifully illustrated by John White, including detailed diagrams of the atomic bombs and the bombing runs on Hiroshima and Nagasaki. In addition, Chun includes maps of the original invasion plans of Japan.
In short, this is an excellent analysis of the decisions and operations leading up to the bombing of Hiroshima and Nagasaki.
