The Great Naktong Offensive was the North Korean Korean People's Army (KPA)'s unsuccessful final bid to break the Pusan Perimeter established by the UN forces. By August, the UN troops had been forced into the 140-mile (230 km) Pusan Perimeter on the southeast tip of the Korean peninsula. For the first time, the UN troops formed a continuous line which the KPA could neither flank nor overwhelm with superior numbers. KPA offensives on the perimeter were stalled and by the end of August all momentum was lost. Seeing the danger in a prolonged conflict along the perimeter, the KPA sought a massive offensive for September to collapse the UN line.

The KPA subsequently planned a simultaneous offensive for their entire army along five axes of the perimeter; and on September 1 intense fighting erupted around the cities of Masan, Kyongju, Taegu, Yongch'on and the Naktong Bulge. What followed was two weeks of extremely brutal fighting as the two sides vied to control the routes into Pusan. Initially successful in some areas, the KPA were unable to hold their gains against the numerically and technologically superior UN force. The KPA, again stalled at the failure of this offensive, was outflanked by the Inchon landings on 15 September and on 16 September the UN forces began their breakout from the Pusan Perimeter.