What was the primary reason the Allies seized Saipan in 1944?

On June 15, 1944, during the Pacific Campaign of World War II (1939-45), U. S. Marines stormed the beaches of the strategically significant Japanese island of Saipan, with a goal of gaining a crucial air base from which the U. S. could launch its new long-range B-29 bombers directly at Japan’s home islands.