On June 15, 1944, U.S. Marines landed on the beaches of Saipan to secure it from the Japanese. Nearly all of the 30,000 Japanese defenders were killed. The airfield on Saipan was originally constructed by the Japanese in 1934 and named Aslito Field. During World War II, the Imperial Japanese Navy Air Service assigned two squadrons of Mitsubishi A6MT Zeros to the airfield in mid-June 1944. These squadrons took part on their defense of the Mariana Islands during the Battle of the Philippine Sea later that month, being almost wiped out by the American forces during the battle.

 

The airfield was seized by the Americans on June 16-17, 1944 during the Battle of Saipan. The airfield was renamed Isely Field after the U.S. Navy Commander Robert H. Isley who was killed on June 13, 1944 while strafing the base. Once in American hands, Isley Field was expanded considerably to support the Twentieth Air Force B-29 Superfortress Operations.

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The 73d Wing was deployed to the newly constructed airfields on Saipan in the Northern Mariana Islands. The 73d Bomb Wing was the first B-29 wing to be assigned to the Marianas, and the first B-29 of the 497th Bomb Group arrived at Isley Field, Saipan on October 12, 1944. The 498th arrived shortly after, with the 499th and 500th Bomb Groups arriving in early November. By December 1944, there were more than 100 B-29s on Saipan.

 

Saipan is the largest island of the Northern Mariana Islands, a chain of 15 tropical islands that belong to the Marianas archipelago in the western Pacific Ocean.

 

On the islands of Tinian, Saipan and Guam there were five major airfields (three on the flat island of Tinian) each constructed as bases that became the launch sites for the large B-29 raids against Japan.