 Ground fighting on the island took place over approximately 35 days; lasting from the landings of February 19 to a final Japanese charge the morning of March 26, 1945.The U.S. invasion, known as Operation Detachment, was charged with the mission of capturing the island's airfields.The Japanese positions on the island were heavily fortified, with vast bunkers, hidden artillery, and 18 kilometers (11 mi) of tunnels.