The Battle of Iwo Jima

By late 1944, the outcome of the war with Japan was no longer in doubt. Though Allied victory was inevitable, other questions remained. What would it take to force a Japanese surrender? How could this be accomplished while minimizing Allied casualties?

Allied strategy was deeply influenced by the split command arrangement that produced two simultaneous offensives across the Pacific. The first, controlled by the Army, ran through the southwest Pacific and included as one of its major objectives the liberation of the Philippines. The second was a drive across the central Pacific led by the Navy. The Army’s Chief of Staff, General George C. Marshall, believed that the next target of the island-hopping campaign should be Formosa. Such a campaign would fall under the control of General Douglas MacArthur, the head of South West Pacific Area. Admiral Chester Nimitz, Commander-in-Chief of the Pacific Fleet and Pacific Ocean Areas, wanted to take a more direct approach to Japan, invading Iwo Jima followed up by landings on Okinawa a few weeks later.

General Henry H. “Hap” Arnold of the Army Air Forces ultimately broke the impasse. B-29s flying from the Marianas were already bombing the Japanese mainland, and Arnold wanted to ensure that they had adequate fighter escorts. He sided with Nimitz, arguing that Iwo Jima would make a good base for the fighters. The intelligence available to Nimitz suggested that Iwo Jima was lightly defended, and he argued that three of the four Marine divisions assigned to the invasion could be used again in the upcoming Okinawa landings just forty days later. The Joint Chiefs approved this plan, and the invasion of Iwo Jima proceeded under the codename Operation Detachment.

Iwo Jima Terrain Map
Naval War College Museum Collection

Amphibious landings are enormously complex operations requiring close coordination between many elements. In an era before computers and PowerPoint, briefers used terrain maps to familiarize Marines, soldiers, sailors, and airmen with their objectives. Arthur E. Jacques of the Naval Photographic Intelligence Center produced the map shown above which was made from rubber, allowing it to be easily rolled up and stored while also providing durability in a marine environment.

Despite careful planning, the conquest of Iwo Jima proved much more difficult than anticipated. American military forces suffered more than 26,000 casualties in capturing the island which took four and a half weeks longer than initially projected. The Army Air Forces did not use the island as a fighter base after all, due to the fact that it was too far from Japan even for long-range escort fighters. Arnold later claimed that 2,251 B-29s made emergency landings there, thus saving the lives of thousands of airmen.

Iwo Jima Terrain Map, Detail Shots 
Naval War College Museum Collection

Even that has been thrown into question, as recent scholarship has shown that most of the B-29 landings were routine training flights and not due to emergencies. Still, the occupation of Iwo Jima denied its use by the Japanese military and brought the U.S. one step closer to the Japanese homeland. American military planners also learned valuable lessons about Japanese defenses and used this information to good effect during the invasion of Okinawa.

Rob Doane

Curator

Naval War College Museum