Atomic Bombing of Nagasaki

Nagasaki had been a shipbuilding and armaments city since the late Edo period, and the Urakami River valley was lined with Mitsubishi plants, including the shipyard, the steel works and the arms (ordnance) works. After Hiroshima was attacked on 6 August 1945, the 509th Composite Group flew a second atomic mission from Tinian; its primary target was Kokura, site of an Army arsenal.

On August 9, 1945, a B-29 bomber 'Bockscar', flown by Maj. Charles Sweeney, carried the plutonium-239 implosion bomb 'Fat Man'. The original target was Kokura, but cloud cover and smoke left from the previous day's raid on Yahata prevented visual aiming on three bomb runs and forced the crew to divert to Nagasaki. At 11:02 the bomb detonated about 500 metres above Matsuyama-machi in the Urakami Valley, with a yield of roughly 21-22 kilotons of TNT. The hypocentre lay north of the city centre, and the surrounding hills limited the area of destruction to some extent.

The explosion killed approximately 40,000 people instantly. By the end of 1945, the death toll reached approximately 70,000; the figure long used by Nagasaki City is 73,884 dead and 74,909 injured, and estimates range from 60,000 to 80,000. About 36% of the city's buildings were destroyed or badly damaged. The Mitsubishi industrial facilities in the city were severely damaged, and Urakami Cathedral, Nagasaki Medical College and Shiroyama National School were wrecked. The dead included mobilised students, labourers from Korea and China, and a small number of Allied prisoners of war. Short of fuel, Bockscar landed on Okinawa. Six days later, on 15 August, Japan announced its acceptance of the Potsdam Declaration.

After the war the hypocentre area became the Peace Park. The Peace Statue by Kitamura Seibo was completed in August 1955, and the Nagasaki Atomic Bomb Victims Memorial Peace Ceremony is held before it every 9 August. The Nagasaki Atomic Bomb Museum opened in April 1996 and the Nagasaki National Peace Memorial Hall for the Atomic Bomb Victims in 2003. On 3 October 2016 five sites (the hypocentre, the former Shiroyama National School building, the old belfry of Urakami Cathedral, the gateposts of the former Nagasaki Medical College and the second torii of Sanno Shrine) were designated a National Historic Site as the 'Nagasaki Atomic Bomb Remains'. As of 9 August 2025 the register of the atomic-bomb dead held 204,708 names.