Iwo Jima is a small volcanic island about 750 miles south-southeast of Tokyo. The island had two operating airfields from which flew Japanese fighters and bombers. From late 1944 to early 1945, the Japanese stationed fighters and bombers on Iwo Jima. Their mission was to intercept the U.S. B-29s bombing Japan and to conduct night bombing raids on the Mariana airfields to disrupt U.S. bombing operations. Japanese bombers conducted about nine significant raids against the Marianas. The night raids were small in scale,  typically 5 to 20 Mitsubishi G4M “Betty” bombers. The raids never seriously curtailed B-29 missions as U.S. forces had ample construction battalions to repair damage quickly. The Japanese air raids from Iwo Jima on the Marianas were annoying but not decisive. Their main effect was psychological and tactical, not strategic.

The island lay virtually under the direct flight path to Tokyo of B-29 bombers operating out of Saipan and Tinian allied airfields. The direct distance was 1,350 miles but in order to avoid Iwo Jima’s fighters, the flight route was 1,700 miles one way. Despite the route, the island served as an early warning station for Japanese mainland defense.

The strategic reason for invading and taking Iwo Jima was to eliminate the early warning capability, the fighter intercepts on the bombers, the nuisance bombing raids on B-29 bases, shorten the route to/from the Japanese home islands for the “finicky” B-29s, and provide an emergency diversion landing site for returning B-29 bombers. This last feature came into use during the intense fighting on Iwo Jima and by war’s end was responsible for saving ~2,400 US Army Air Force pilots and flight crews.