The death toll from the explosion, on August 9, 1945, was about 40,000. But, as in Hiroshima, thousands more died later due to radiation exposure from the atomic bomb. American military strategists believed that the first A-bomb, on Hiroshima, would force Japan’s leaders to surrender. But when they did not, the second bomb was dropped on Nagasaki, an important seaport and commercial city. That catastrophic attack on Japan brought an end to the war, on August 14. Japan signed the surrender agreement on September 2 aboard the U.S. battleship Missouri, in Tokyo Bay.