The United States detonated two nuclear weapons over the Japanese cities of Hiroshima and Nagasaki on August 6 and 9, 1945, respectively, with the consent of the United Kingdom, as required by the Quebec Agreement. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the only uses of nuclear weapons in armed conflict.
In the final year of World War II, the Allies prepared for a very costly invasion of the Japanese mainland. This undertaking was preceded by a conventional and firebombing campaign which devastated 67 Japanese cities. The war in Europe had concluded when Germany signed its instrument of surrender on May 8, 1945, and the Allies turned their full attention to the Pacific theater. The Allies called for the unconditional surrender of the Imperial Japanese armed forces in the Potsdam Declaration on July 26, 1945, the alternative being "prompt and utter destruction". Japan ignored the ultimatum and the war continued.