After the battle, Tinian became an important base for further Allied operations in the Pacific campaign. Camps were built for 50,000 troops. Fifteen thousand Seabees turned the island into the busiest airfield of the war, with six runways for attacks by United States Army Air Forces B-29 Superfortress bombers on enemy targets in the Philippines, the Ryukyu Islands, and mainland Japan, including the March 9/10 1945 "Operation Meetinghouse" firebombing of Tokyo and the atomic bombings of Hiroshima and Nagasaki. North Field was built over Airfields No. 1 and 3, and became operational in February 1945, while West Field was built over Airfield No. 2, and became operational in March 1945.