The plan for the invasion of Japan consisted of three parts. First was Operation Olympic - the descent on the southern island of Kyushu in November 1945. This operation was to seize enough of the island to act as a base for further operations against the main island of Honshu. Second was Operation Coronet planned for March 1946. The third featured a Soviet attack (they had until then been at peace with Japan) against Japanese-occupied Manchuria. This was to prevent the Japanese transferring forces to the home islands once the invasion got underway.
Casualties were expected to be very heavy and it was hoped that the use of atomic bombs might shock the Japanese into surrendering. The first bomb was dropped on Hiroshima on 6 August 1945. On 8 August the Soviet Union declared war on Japan and launched a massive attack in Manchuria. In some ways the Soviet blow had the greater diplomatic and political impact. On 9 August a second atomic bomb was dropped on the city of Nagasaki. That night the Japanese government were ordered to surrender by the Emperor. On 15 August 1945 the Japanese surrendered.