The Battle of Iwo Jima was fought between the United States and the Japanese Empire, in February and March 1945 during the Pacific Campaign of World War II. Ground fighting on the island took place over approximately 36 days; lasting from the landings of February 17 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.