In its 36 days of combat on Iwo Jima, the V Amphibious Corps killed approximately 22,000 Japanese soldiers and sailors. The cost was staggering. The assault units of the corps—Marines and organic Navy personnel—sustained 24,053 casualties, by far the highest single-action losses in Marine Corps history. Of these, a total of 6,140 died. Roughly one Marine or corpsman became a casualty for every three who landed on Iwo Jima.
According to a subsequent analysis by military historian Dr. Norman Cooper, "Nearly seven hundred Americans gave their lives for every square mile. For every plot of ground the size of a football field, an average of more than one American and five Japanese were killed and five Americans wounded."
The assault infantry units bore the brunt of these losses. Captain William T. Ketcham's Company I, 3d Battalion, 24th Marines, landed on D-day with 133 Marines in the three rifle platoons. Only nine of these men remained when the remnants of the company reembarked on D+35. Captain Frank C. Caldwell reported the loss of 221 men from Company F, 1st Battalion, 26th Marines. At the end, a private first class served as platoon commander for Caldwell's merged first and second platoons. Elsewhere in the 1st Battalion, 26th Marines, Captain Tom Fields relinquished command of Company D on the eighth day to replace the battalion executive officer. Rejoining his company at the end of the battle, Fields was sickened to find only 17 of the original 250 men still in the ranks. Company B, 1st Battalion, 28th Marines, went through nine company commanders in the fighting; 12 different Marines served as platoon leader of the second platoon, including two buck privates. Each division, each regiment, reported similar conditions.
