 Yokohama was rebuilt, only to be destroyed again by U.S. air raids during World War II.An estimated seven or eight thousand people were killed in a single morning on May 29, 1945 in what is now known as the Great Yokohama Air Raid, when B-29s firebombed the city and in just one hour and nine minutes reduced 42% of it to rubble.During the American occupation, Yokohama was a major transshipment base for American supplies and personnel, especially during the Korean War.