Incheon landing, September 15, 1950

The Incheon landing, September 15, 1950, was the amphibious assault that turned the Korean War from a desperate effort to hold the line into a campaign of rapid advance. Its success rested on the element of surprise at a port whose tides, seawalls, and lack of beaches seemed to make a landing nearly unworkable; its consequences extended beyond the battlefield, bringing the future of the 38th parallel into immediate question.

A gamble against the geography

By early September, the possibility of a landing behind North Korean lines had been discussed for weeks, but the details remained uncertain and the Joint Chiefs of Staff were skeptical. In Tokyo, General MacArthur presented his plan to W. Averell Harriman and Matthew Ridgway in a two-and-a-half-hour briefing. Both were won over, and Harriman urged Harry S. Truman to regard the operation as a possible means of salvation.

The proposed target was Incheon, on the western shore of the Korean Peninsula, about 200 miles northwest of Pusan. Its natural conditions made the assault unusually hazardous: tides could reach 30 feet or more, there were no beaches, and landing craft would have to approach the city’s seawalls. The usable window was narrow. After two hours beyond high tide, the craft would be stranded in mud, while the tide would prevent reinforcements from landing until it rose again.

Omar Bradley regarded the proposal as the riskiest military plan he had heard. General MacArthur argued that its apparent impracticability could protect the element of surprise, pointing to the Japanese landing at Incheon in 1904 and comparing the challenge to the cliffs scaled at Quebec in 1759. The timetable added pressure: the operation needed to begin before the Korean winter brought further casualties, and the tides would be suitable on September 15. Harriman laid out the difficulties to Truman, who sent him to consult Louis Johnson and Bradley without making an immediate commitment. Harriman nevertheless left believing that Truman approved.

Authorization and launch

After a final Oval Office session on Incheon, the Joint Chiefs of Staff gave General MacArthur the go-ahead on September 9. The landing was scheduled for September 15, less than a week later. In the same period, Truman asked George C. Marshall to return to government as Secretary of Defense. Marshall agreed, despite warning that his appointment might revive accusations concerning the fall of Chiang Kai-shek’s government in China and harm the administration he hoped to help.

The landing began in the early hours of September 15 in Korea, which was the afternoon of September 14 in Washington, D.C. The assault achieved the surprise General MacArthur had predicted. A force of 262 ships and 70,000 men from the U.S. Tenth Corps took part, with the 1st U.S. Marine Division leading the attack. Incheon fell in little more than a day, an outcome that turned the plan’s severe geographical disadvantages into part of its operational success.

The reversal on the peninsula

The landing’s effects unfolded alongside an advance from the south. Eleven days after the assault, Seoul was retaken. Meanwhile, Walton Walker’s Eighth Army broke out of the Pusan Perimeter and began moving north, joining the pressure on the North Korean forces. By September 27, more than half of the North Korean Army had been trapped in a large pincer movement. On October 1, United Nations forces reached the 38th parallel, and South Korea was under United Nations control.

The speed of the change astonished observers in Washington, D.C., and the country greeted the result with exultation. Truman sent General MacArthur a jubilant message saluting the forces for their achievement. What had begun as a struggle over whether United Nations forces could survive in Korea had, in two weeks, become an entirely different war.

The new question of advance

Victory brought a decision the landing itself could not settle: whether to stop at the 38th parallel or cross it in pursuit of the North Korean Army and the Communist regime of the north, with the stated aim of unifying the country. General MacArthur supported hot pursuit, as did the Joint Chiefs of Staff, the press, politicians in both parties, and most of the American public. The success at Incheon had changed the immediate military outlook, but it had also widened the stakes from defending South Korea to deciding how far the war should go.