Truman by David McCullough:
In the early house of September 15—it was afternoon in Washington, September 14—the amphibious landing at Inchon began. As promised by MacArthur, the attack took the enemy by total surprise, and as also promised by MacArthur, the operation was an overwhelming success that completely turned the tables on the enemy.
The invasion force numbered 262 ships and 70,000 men of the Tenth Corps, with the 1st Marine Division leading the assault. Inchon fell in little more than a day. In eleven days Seoul was retaken. Meantime, as planned, General Walker’s Eighth Army broke out of the Pusan Perimeter and started north. Seldom in military history had there been such a dramatic turn in fortune. By September 27 more than half the North Korean Army had been trapped in a huge pincer movement. By October 1, U.N. forces were at the 38th parallel and South Korea was in U.N. control. In two weeks, it had become an entirely different war.