The Battle of the Pusan Perimeter was a large-scale battle between United Nations Command and North Korean forces lasting from August 4 to September 18, 1950. It was one of the first major engagements of the Korean War. An army of 140,000 UN troops, having been pushed to the brink of defeat, were rallied to make a final stand against the invading Korean People's Army, 98,000 men strong.
UN forces, having been repeatedly defeated by the advancing KPA, were forced back to the "Pusan Perimeter", a 140-mile defensive line around an area on the southeastern tip of South Korea that included the port of Busan. The UN troops, consisting mostly of forces from the Republic of Korea Army, United States, and United Kingdom mounted a last stand around the perimeter, fighting off repeated KPA attacks for six weeks as they were engaged around the cities of Daegu, Masan, and Pohang and the Nakdong River. The massive KPA assaults were unsuccessful in forcing the UN troops back further from the perimeter, despite two major pushes in August and September.