When North Korea sought to reunify with South Korea by force on June 25, 1950, a small peninsula in East Asia turned into an international hot spot amid the steadily intensifying Cold War. The United Nations Security Council roundly condemned the invasion (while the Soviet Union was boycotting the council and thus in no position to veto it). Military contingents from the United States and 20 other nations joined forces with the Republic of Korea Army (ROKA) in what President Harry S. Truman termed a “police action.”

View striking images from the conflict from our November 2020 issue:

  • Marines climb scaling ladders to secure a beachhead at Inchon, South Korea, on Sept. 15, 1950. / National Archives
  • Backed by an M26 Pershing tank, Marines advance into North Korea in 1950. / David Douglas Duncan Collection, University of Texas at Austin
  • American airborne troops and supplies parachute to frozen ground during a 1951 U.N. operation. / National Archives
  • Australian soldiers ride an M4A3E8 Sherman tank 50 miles north of the North Korean capital of Pyongyang during the U.N. advance in 1950. / Hulton Deutsch, Getty Images
  • Chinese and North Korean soldiers celebrate what they regard as a victory on learning of the armistice in July 1953. / Hulton Deutsch, Getty Images
  • A South Korean refugee carrying her brother pauses in front of a stalled M48 Patton tank in June 1951. / Hulton Deutsch, Getty Images
  • Confronting the Chinese People’s Volunteer Army, on the offensive since late November 1950, a flamethrower team of the 1st Marine Division flushes enemy troops from hiding on May 5, 1951. / U.S. Marine Corps History Division
  • Marines withdrawing from North Korea’s Chosin Reservoir on Dec. 26, 1950, attack a Chinese position just hit by a U.S. Navy F4U-5 Corsair fighter-bomber. / U.S. Marine Corps History Division
  • A U.S. soldier comforts another whose buddy was killed, as a medic fills out casualty tags, on North Korea’s Haktang-ni high ground in 1950. / National Archives


The communist Korean People’s Army (KPA) overran the South Korean capital of Seoul on June 28, and by August the ROKA and the U.S. Eighth Army held one-tenth of the country with the city of Pusan at their backs. There, however, they regained the initiative. On September 15 General of the Army Douglas MacArthur made an end run to land American and South Korean troops at Inchon. The next day U.N. forces broke out of the Pusan Perimeter, and the KPA began disintegrating. Seoul was retaken within 10 days, and MacArthur pushed on into North Korea.

However, on October 19 the nascent People’s Republic of China, perceiving the imminent collapse of North Korea as an existential threat, intervened with its 250,000-strong People’s Volunteer Army, which by December drove back U.N. forces. Seoul fell again on Jan. 4, 1951, but U.N. firepower took a heavy toll on the Chinese. On May 20 U.S. forces under Gen. Matthew Ridgway launched a counteroffensive that retook Seoul by mid-June and drove communist forces back north of the 38th parallel. The war continued there in a bloody stalemate until all sides agreed to an armistice and cease-fire on July 27, 1953. The participants have yet to sign a treaty ending the Korean War.

While some Americans regard Korea as “the first war we lost,” the thriving Republic of Korea suggests the United States and the U.N. achieved their objectives. China also got what it wanted by preserving North Korea as a buffer zone, leaving the latter nation as the conflict’s only outright loser, having failed in its goal to reunify the peninsula. MH

This article appeared in the November 2020 issue of Military History magazine. For more stories, subscribe here and visit us on Facebook: