In hindsight, given the number of casualties, the necessity and long-term significance of the island’s capture to the outcome of the war became a contentious issue and remains disputed. The Marines, who suffered the actual casualties, were not consulted in the planning of the operation. As early as April 1945, retired Chief of Naval Operations William V. Pratt stated in Newsweek magazine that considering the “expenditure of manpower to acquire a small, God-forsaken island, useless to the Army as a staging base and useless to the Navy as a fleet base … one wonders if the same sort of airbase could not have been reached by acquiring other strategic localities at lower cost.”
The lessons learned on Iwo Jima served as guidelines for the following Battle of Okinawa and the planned invasion of the Japanese homeland. For example, “because of the casualties taken at Iwo Jima on the first day, it was decided to make the preparatory bombardment the heaviest yet delivered on to a Pacific island”. Also, in the planning for a potential attack on the Japanese home islands, it was taken into account that around a third of the troops committed to Iwo Jima and again at Okinawa had been killed or wounded.
The justification for Iwo Jima’s strategic importance to the United States’ war effort has been that it provided a landing and refueling site for long-range fighter escorts. These escorts proved both impractical and unnecessary, and only ten such missions were ever flown from Iwo Jima. Japanese fighter aircraft based on Iwo Jima sometimes attacked AAF planes, which were vulnerable on their way to Japan because they were heavily laden with bombs and fuel.
However, although some Japanese interceptors were based on Iwo Jima, their impact on the American bombing effort was marginal; in the three months before the invasion only 11 B-29s were lost as a result. The Superfortresses found it unnecessary to make any major detour around the island. Marines from the 24th Marine Regiment during the Battle of Iwo Jima.
The Japanese on Iwo Jima had radar and were thus able to notify their comrades at home of incoming B-29 Superfortresses flying from the Mariana Islands. However, the capture of Iwo Jima did not affect the Japanese early-warning radar system, which continued to receive information on incoming B-29s from the island of Rota (which was never invaded).
As early as 4 March 1945, while fighting was still taking place, the B-29 Dinah Might of the USAAF 9th Bomb Group reported it was low on fuel near the island and requested an emergency landing. Despite enemy fire, the airplane landed on the Allied-controlled section of the island (South Field), without incident, and was serviced, refueled and departed. In all, 2,251 B-29 landings on Iwo Jima were recorded during the war.
Moskin records that 1,191 fighter escorts and 3,081 strike sorties were flown from Iwo Jima against Japan. Some downed B-29 crewmen were saved by air-sea rescue aircraft and vessels operating from the island, but Iwo Jima was only one of many islands that could have been used for such a purpose. As for the importance of the island as a landing and refueling site for bombers, Marine Captain Robert Burrell, then a history instructor at the United States Naval Academy, suggested that only a small proportion of the 2,251 landings were for genuine emergencies, the great majority possibly being for minor technical checkups, training, or refueling.
According to Burrell,This justification became prominent only after the Marines seized the island and incurred high casualties. The tragic cost of Operation Detachment pressured veterans, journalists, and commanders to fixate on the most visible rationalization for the battle.
The sight of the enormous, costly, and technologically sophisticated B-29 landing on the island’s small airfield most clearly linked Iwo Jima to the strategic bombing campaign. As the myths about the flag raisings on Mount Suribachi reached legendary proportions, so did the emergency landing theory in order to justify the need to raise that flag. In publishing The Ghosts of Iwo Jima, Texas A&M University Press said that the very losses formed the basis for a “reverence for the Marine Corps” that not only embodied the “American national spirit” but ensured the “institutional survival” of the Marine Corps.