S1, E4: With U.S. and U.N. forces locked in the struggle to break out from the Pusan Perimeter, General MacArthur put in place what was perhaps the most remembered aspect of the Korean War: The amphibious landing at Inchon. The 5th Marine Regiment landed on Wolmi-do Island in Inchon Harbor on September 15, 1950 to begin the action. By the next day American forces took Seoul and were now on the offensive.