On what date did the United States drop the first atomic bomb used in war on Hiroshima?

The United States dropped the first atomic bomb used in war on Hiroshima on August 6, 1945.

A B-29 bomber named Enola Gay dropped the uranium gun-type bomb Little Boy over Hiroshima at about 8:15 a.m. local time. The explosion devastated much of the city and caused enormous civilian casualties, both immediately and later from injuries and radiation effects.

Hiroshima was a major military and industrial center, but it also contained a large civilian population. The bombing followed the Potsdam Declaration's demand for Japan's surrender and preceded the Soviet declaration of war and the Nagasaki bombing.

The Hiroshima attack became one of the central events in Japan's decision to surrender, although historians continue to debate the relative weight of the atomic bombings, the Soviet entry into the war and internal Japanese political divisions. The second atomic bomb was used against Nagasaki three days later.