Three days separated the atomic bombings of Hiroshima and Nagasaki in August 1945.
The United States bombed Hiroshima on 6 August 1945 with the uranium weapon known as Little Boy. On 9 August, it dropped the plutonium weapon Fat Man on Nagasaki, making the interval three calendar days.
The bombings occurred during the final phase of the Pacific War. Japan's government had already been warned in the Potsdam Declaration, but it did not immediately accept the Allied demand for surrender. The Soviet Union also declared war on Japan on 8 August and invaded Japanese-held Manchuria beginning 9 August.
Japan announced its surrender on 15 August, six days after the Nagasaki bombing. The formal Instrument of Surrender was then signed on 2 September aboard USS Missouri. The sequence is often simplified, but the atomic attacks, Soviet entry into the war, imperial decision, broadcast announcement, and formal signing were separate events.