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In March 1944, the Japanese 31st Army, commanded by General Hideyoshi Obata, was activated to garrison this inner line. (Note that a Japanese army was about the size of an American, British Army, or Canadian Army corps. The Japanese Army had many armies, but the U.S. Army only had ten at its peak, with the 4th Army, the 6th Army, the 8th Army, and the 10th Army being in the Pacific Theater. Also, the 10th Army only fought on Okinawa in the spring of 1945.)
The American invasion, designated Operation Detachment, had the purpose of capturing the island with its two airfields: South Field and Central Field. The strategic objectives were twofold: the first was to provide an emergency landing strip for battle-damaged B-29s unable to make it back to US air bases in the Marianas Tinian, Saipan, Guam. The second was to provide air fields for fighter escorts, long-range P-51s, to provide fighter coverage to the bombers. The five-week battle saw some of the fiercest and bloodiest fighting of the Pacific War.
The IJA positions on the island were heavily fortified, with a dense network of bunkers, hidden artillery positions, and 18 km (11 mi) of tunnels. The American ground forces were supported by extensive naval artillery, and had complete air supremacy provided by U.S. Navy and Marine Corps aviators throughout the battle.
Japanese combat deaths numbered three times the number of American deaths although, uniquely among Pacific War Marine battles, American total casualties (dead and wounded) exceeded those of the Japanese. Of the 21,000 Japanese soldiers on Iwo Jima at the beginning of the battle, only 216 were taken prisoner, some of whom were captured because they had been knocked unconscious or otherwise disabled. The majority of the remainder were killed in action, although it has been estimated that as many as 3,000 continued to resist within the various cave systems for many days afterwards, eventually succumbing to their injuries or surrendering weeks later.
The IJA positions on the island were heavily fortified, with a dense network of bunkers, hidden artillery positions, and 18 km (11 mi) of tunnels. The American ground forces were supported by extensive naval artillery, and had complete air supremacy provided by U.S. Navy and Marine Corps aviators throughout the battle.
Japanese combat deaths numbered three times the number of American deaths although, uniquely among Pacific War Marine battles, American total casualties (dead and wounded) exceeded those of the Japanese. Of the 21,000 Japanese soldiers on Iwo Jima at the beginning of the battle, only 216 were taken prisoner, some of whom were captured because they had been knocked unconscious or otherwise disabled. The majority of the remainder were killed in action, although it has been estimated that as many as 3,000 continued to resist within the various cave systems for many days afterwards, eventually succumbing to their injuries or surrendering weeks later.
Though ultimately victorious, the American victory at Iwo Jima had come at a terrible price. According to the official Navy Department Library website, "The 36-day (Iwo Jima) assault resulted in more than 26,000 American casualties, including 6,800 dead." By comparison, the much larger scale 82-day Battle of Okinawa lasting from early April until mid-June 1945 (involving five U.S. Army and two Marine Corps divisions) resulted in over 62,000 U.S. casualties, of whom over 12,000 were killed or missing. Iwo Jima was also the only U.S. Marine battle where the American casualties exceeded the Japanese, although Japanese combat deaths numbered three times as many as American deaths. Two US Marines were captured during the battle, neither of whom survived their captivity. The USS Bismarck Sea was also lost, the last U.S. aircraft carrier sunk in WW2. Because all civilians had been evacuated, there were no civilian casualties at Iwo Jima, unlike at Saipan and Okinawa.
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. By the time Iwo Jima had been captured, the bombing campaign against Japan had switched from daylight precision bombing to nighttime incendiary attacks, so fighter escorts were of limited utility.
Joe Rosenthal's Associated Press photograph of the raising of the U.S. flag on top of the 169 m (554 ft) Mount Suribachi by six U.S. Marines became an iconic image of the battle and the American war effort in the Pacific.
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. By the time Iwo Jima had been captured, the bombing campaign against Japan had switched from daylight precision bombing to nighttime incendiary attacks, so fighter escorts were of limited utility.
Joe Rosenthal's Associated Press photograph of the raising of the U.S. flag on top of the 169 m (554 ft) Mount Suribachi by six U.S. Marines became an iconic image of the battle and the American war effort in the Pacific.
