 The 81st Infantry Division also suffered heavy losses with 3,300 casualties during their tenure on the island.Postwar statisticians calculated that it took U.S. forces over 1500 rounds of ammunition to kill each Japanese defender and that, during the course of the battle, the Americans expended 13.32 million rounds of .30-calibre, 1.52 million rounds of .45-calibre, 693,657 rounds of .50-calibre bullets, 118,262 hand grenades, and approximately 150,000 mortar rounds.The battle was controversial in the United States due to the island's lack of strategic value and the high casualty rate.