U.S. Tenth Corps

The U.S. Tenth Corps was a major United Nations force in the Korean War, most consequentially in the Incheon landing and the subsequent advance into North Korea. Its sudden success in September 1950 helped transform a campaign focused on survival into an offensive, but its later position on the eastern side of the peninsula became part of a dangerous division of forces that Chinese troops exploited.

The Incheon Landing

On September 15, 1950, the amphibious landing at Incheon began with an invasion force of 262 ships and 70,000 U.S. Tenth Corps troops. The 1st Marine Division led the assault. Incheon fell in little more than a day, and Seoul was retaken within eleven days. At the same time, Walton Walker’s Eighth Army broke out of the Pusan Perimeter and advanced north. By September 27, more than half of the North Korean Army had been caught in a large pincer movement; by October 1, United Nations forces had reached the 38th parallel and South Korea was back under United Nations control. The landing marked a dramatic reversal in the war’s fortunes.

The Advance and Division of Forces

After the success at Incheon, the question facing U.S. leaders shifted from whether United Nations forces could hold on in Korea to whether they should cross the 38th parallel and try to destroy the northern regime. As the advance continued, Douglas MacArthur divided his forces: the U.S. Tenth Corps moved up the eastern side of the peninsula, while the Eighth Army advanced on the west. The Joint Chiefs questioned the risk of this arrangement. MacArthur nevertheless pressed for a decisive offensive, and no one, including Harry S. Truman, stopped the plan before it began.

The Retreat from Chosin Reservoir

The division left the forces vulnerable when Chinese troops attacked their flanks. In the northeast, the U.S. Tenth Corps faced a retreat that the account describes as more severe than the Eighth Army’s withdrawal from the Chongchon River. The 1st Marine Division fought its way from the Chosin Reservoir toward Hungnam, a distance of forty miles, before evacuation from the port. The contrast with the triumph at Incheon was stark: the corps that had helped turn the war in September was soon caught in a retreat under winter conditions and overwhelming pressure.