The Hiroshima Bomb Was
The Hiroshima Atomic Bomb

The Hiroshima Bomb was untested.

A "gun-type" weapon, it used uranium to provide its destructive power. The bomb named “Little Boy” weighed 4,000 kg (8,900 lb), was 3 meters (10 ft) in length and 71 cm (28 inches) in diameter.

Due to the short supply of enriched uranium at the time and the confidence of the designers that the bomb would work, the atomic bombing of Hiroshima was a test in itself. 

Transported by the B-29 Superfortress bomber “Enola Gay” the bomb was dropped at 8:15am on August 6th 1945, 580 meters (1,900 feet) above Hiroshima. 

Once leaving the aircraft, “Little Boy” took 57 seconds to fall before detonating at its predetermined height. However, it missed the designated aiming point, the Aioi Bridge by approximately 240 meters (800 ft) because of a crosswind, its blast centering above Shima Surgical Clinic.

Perhaps no one in Japan on that day would have any idea of the Hiroshima aftermath that was to follow.

Why Was Hiroshima Bombed?

Hiroshima was chosen as the primary target out of a short list of 3 other cities: Nagasaki, Kokura and Niigata.

The main reason it was chosen, is thought to be the fact that unlike the other targets, it did not have an allied prisoner of war camp. 

Also Hiroshima actually had many military factories and facilities as well as a port, none of which had been bombed (on purpose), so that the full effect of the atomic bomb could be measured.