Central to any discussion of the necessity for the use of the atomic bomb to help bring about an end to the Second World War in the Pacific is the issue of the projected cost in blood of an Allied invasion of the Japanese home islands.  Nevertheless, with the exception of John Skates' 1994 book Invasion of Japan: Alternative to the Bomb, this critical question has been largely unexamined.  As a result both sides of in the debate have passionately argued their positions with a shocking level of ignorance.  Building on his earlier work on the subject, in Hell to Pay: Operation Downfall and the Invasion of Japan, 1945-1947, military historian D.M. Giangreco, author of The Soldier from Independence: A Military Biography of Harry Truman and many other works, provides a welcome investigation of the costs of an invasion of the Japanese home islands based on a careful examination of the invasion plans and defense preparations. This work succeeds because it provides a detailed understanding of the military calculations of both sides during the final days of the war, which leads to an evaluation of the likely course of an Allied invasion.

Giangreco argues cogently that the Japanese armed forces were relatively confident in their ability to resist an Allied invasion. The Japanese had accumulated thousands of kamikaze aircraft, far more than the Allies had estimated, many of which were older models that were nearly invisible to radar, plus a wide variety of suicide naval craft, an army of approximately three million men, and a rapidly expanding home defense force.  What Japan lacked in quality and power projection, it made up for in numbers and a fierce dedication to the defense of the homeland.  Although most Japanese planners anticipated heavy losses, some estimating as many as 20 million dead, they believed that they could extract so high a price in blood from the Allies that they would be able to secure an acceptable end to the war.

Alternatively, Giangreco depicts the Allies as confident in their ability to win, but deeply concerned regarding the costs of their victory, citing, for example, Marine Major General Graves B. Erskine, who remarked, "[V]ictory was never in doubt. Its cost was.  What was in doubt, in all our minds, was whether there would be any of us left to dedicate our cemetery at the end, or whether the last Marine would die knocking out the last Japanese gun and gunner."  This fatalism was underscored by American defense planners who ordered an additional 500,000 Purple Heart decorations made in anticipation of massive losses, a stockpile so large it proved sufficient to cover American casualties in wars over the next 50 years.

According to Giangreco, the atomic bombs were a clear blessing because they ended the "mutual suicide pact" and almost certainly saved lives on both sides.  Although this claim will offend and shock some readers, the wealth of primary source evidence provided by Giangreco clearly supports this assertion.  While this work is very detailed and technical in places, it is well written and will keep readers engaged with its sense of impending disaster.  This book is a must read for any student of World War II, whether scholar or interested citizen, and will likely remain the standard work on the subject for years to come.