mgsupgs blog: "Hiroshima"

“At the time of the bombing, Hiroshima was a city of great industrial and military importance. In addition, several military camps were located nearby, including the headquarters of the Fifth Division and the headquarters of the Second Main Army of Field Marshal Sunroku Hata, who commanded the defense of all of Southern Japan.

Hiroshima was an important supply base for the Japanese army. The city was a communications center and a rallying point for troops. It was one of several Japanese cities deliberately left untouched by American bombing, allowing for an ideal measurement of the damage caused by a nuclear bomb. According to other sources, General Spaatz reported that Hiroshima was the only target city without prisoner of war camps, and therefore Washington decided to give it the highest priority."