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Battle of the Busan Perimeter
August–September 1950· Battle· Wars & invasions
Well documentedSolid records, physical evidence or scientific consensus.
Six weeks of defensive fighting in 1950 in which UN and South Korean troops held a small corner of southeast Korea around Busan.
See it on the Korean History map →What happened
By early August 1950 North Korean forces had overrun most of the South. The US Eighth Army under General Walton Walker and the South Korean army held a line about 230 km long, using the Nakdong River as a moat; Koreans call it the 낙동강 방어선 (Nakdong River defense line). Troops and supplies poured in through Busan's port. At Dabu-dong north of Daegu and elsewhere, attacks were beaten back until defenders broke out on September 16.
Why it matters
Holding Busan kept South Korea and the UN in the war and kept a port open for the counterattack.
How we know
US Army official histories, South Korean military records, captured North Korean documents, and memorials such as the Dabu-dong battle site near Chilgok.
Still debated
How close the line came to breaking during the early-September offensives is debated, and casualty figures for both sides vary by source.
Connections (2)
▸Battle of the Busan Perimeter held until Incheon Landing (Operation Chromite)Well documented
The connection
By holding the pocket around Busan, UN and South Korean troops pinned most of North Korea's army in the far south, at the end of long, exposed supply lines. That made a landing far behind the front at Incheon worthwhile; on September 16 the Eighth Army broke out, linking up with the landing force near Osan ten days later.
When and how
Southeast Korea and Incheon, August–September 1950; Walton Walker's Eighth Army held the line while MacArthur's X Corps landed on September 15.
How we know
US Army official histories and operational orders document the timed breakout and the link-up of the two forces.
Debates and open questions
Whether pulling a Marine brigade off the perimeter for Incheon put the line at risk, and whether the breakout could have succeeded without the landing.
▸Battle of the Busan Perimeter was the UN's last-ditch stand early in Korean WarWell documented
The connection
Within six weeks of the June 25 invasion, North Korea held all but a corner of the South. The perimeter was the last ground the South and the UN still controlled; losing it would likely have ended the war with a North Korean victory. The South's government ran the war from Busan, its temporary capital.
When and how
August 4 – September 18, 1950; the US Eighth Army under Walton Walker and the South Korean army against the North Korean army.
How we know
US Army official histories, South Korean military records and captured North Korean documents.
Debates and open questions
Why North Korea's army paused for several days after taking Seoul on June 28, giving US troops time to arrive, is still debated.