The regiment's next assignment would prove to be their most difficult; in the spring of 1945, the Ohioans fought in the Battle of Iwo Jima. In the early days of the Marine landings, the 147th was ordered to climb from landing craft with grappling hooks to scale a high ridge about 3/4 mile from Mount Suribachi. The mission was to fire on the enemy opposing the Marine landings on the beaches below. They were soon pinned down by heavy Japanese fire, and engaged in non-stop fighting for 3 months. Once the island was declared secure, the regiment was ostensibly there to act as a garrison force, but they soon found themselves locked in a bitter struggle against thousands of stalwart defenders engaging in a last-ditch guerilla campaign to harass the Americans. Using well-supplied caves and tunnel systems, the Japanese resisted American advances. For three months, the 147th methodically scowered the island, using flamethrowers, grenades, and satchel charges to ferret out the enemy. Some sources credit the regiment with killing at least 6,000 Japanese soldiers in those anonymous and merciless small unit actions. The 147th would go on to fight in the bloody Battle of Okinawa, once again in charge of rooting out stubborn Japanese defenders who remained even after the island was declared secure. Company D, which remained on the island of Tinian, earned the distinction of transporting and guarding the Little Boy atomic bomb. When the war ended on 2 September 1945, the 147th Infantry was sent home piecemeal, and the last men to return home arrived in March 1946.