The first atomic bomb was dropped on the Japanese city of Hiroshima to force the Japanese Imperial forces to surrender. They did not do so until after a second atomic bomb was dropped on Nagasaki on 9 August 1945. The death toll from both devices, by the end of 1945, stood at 220,000. More people succumbed to the after-effects of the bombs in following years.
Never again. But the same was said at the end of World War I and II.
However, should nuclear war ever occur, it will be the end of all wars.
As there won't be anyone left to go to war for or against.