The 19 February 1945 American invasion of Iwo Jima in the Bonin islands was one of those peculiar events that means different things to different people. The Bonin archipelago (also called the Ogasawara islands) is a volcanic desert: Iwo Jima, the largest of the islands, had no natural water sources and no place that could be used as a harbor. The only reason anyone ever went there before the 1940s was because it was empty. An American whaling outpost was established there in the 1830s after Spain and Britain had laid claim to it over the centuries, and Japan was the last to claim ownership in 1862. No permanent residents were ever “permanent,” but transient fisher folk.
By early 1945, it was clear that the Americans were headed for the home islands of Japan. Japan had fortified the place and built air fields, they realized that they could not hold the Bonins. The Japanese 31st Army, therefore, would be sacrificed in place. The scanty air units were withdrawn in the face of fifty-odd American aircraft carriers.
At the time, the reasoning given for the invasion was to provide a fighter escort base for the B-29s attacking Japan out of the Marianas islands, and as an emergency landing field for crippled bombers. About halfway between Japan and Saipan, the northernmost of the Marianas, this claim passes basic geographic muster, But since the place was useless as a base for either the Army ground forces or the Navy, did the Air Force really need a base with no natural water?
Even the “fighter escorts for the bombers” claim was dubious. Army fighters had the range to reach some of the big Honshu Island of Japan from the Bonins, but lacked the navigational equipment necessary for long flights over water. Further, the Air Forces were changing tactics since their European-style high level daylight bombing wasn’t working in the Pacific.
After some 25,000 casualties (nearly 7,000 dead) in the six weeks fighting for Iwo Jima (Chichi Jima, a smaller rock with fewer flat spaces, its own water and a small harbor to the north, fell almost bloodlessly in less than a week) it raises a question: how many Marine lives does it take to save Army Air Force lives? Of the 2,600 bombers that landed there, less than half “needed” the emergency fields, according to one estimate. In this view, then, some 13,000 Army air crewman were saved. The Japanese lost over 18,000 over the sulfurous wastelands. “Worth the cost” has a whole new meaning with such numbers. Furthermore, there is a school of thought that suggests that the three Marine divisions used in the Bonins were used up to be kept away from Douglas MacArthur in the Philippines, or his plan for Formosa. Idle, those 50,000 men and supporting fleets were a tempting tool. Deployed, they were beyond MacArthur’s reach.
Ultimately, however, like Peleliu, the Japanese needed the Bonins more than the Americans did, and that was the point. The Americans were taking strategic targets from the Japanese because they could, and each one hurt. But too, like Okinawa would in a few months, it demonstrated to the Marines what the Army had found out on Saipan: the Japanese would fight to the death; military, civilian, man, woman, child–it mattered not. What Were They Thinking: A Fresh Look at Japan At War, 1941-45 is a study of the Japanese mindset, available at fine bookstores everywhere.