The committee to decide which cities would be erased from history met in 1945.

The Decision That Would Vaporize Cities: Trinity Test Approved

America prepares to change warfare forever

In April 1945, the U.S. approved the use of atomic weapons on Japan, culminating in the bombings of Hiroshima and Nagasaki that killed over 200,000 people and ended World War II.

In April 1945, as German defeat became inevitable and the war in the Pacific ground on at enormous cost, American officials made decisions that would culminate in the atomic bombings of Japan. The Manhattan Project — the secret $2 billion effort to build nuclear weapons — had employed over 130,000 workers at its peak.

The moral and strategic debates within the Truman administration were intense. Military planners estimated that an invasion of the Japanese home islands might kill up to a million American soldiers and many times that number of Japanese. The bomb, however horrific, might shorten the war and ultimately save lives.

Scientists on the project were divided. Some, including Leo Szilard, circulated petitions against using the bomb on cities without warning. Others, including J. Robert Oppenheimer, concluded the bomb's use was necessary. The target selection committee ruled out Kyoto — Japan's cultural capital — but identified Hiroshima, Nagasaki, Kokura, and Niigata as primary targets for their military significance and size.

When the Trinity test succeeded on July 16, 1945, and the bombs fell on Hiroshima and Nagasaki in August, the nuclear age had arrived. The decision…

💡 The bomb dropped on Nagasaki was a plutonium bomb — different design from the uranium bomb dropped on Hiroshima. Kokura was the primary target but was spared by cloud cover.