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Historical ConflictPusan Perimeter

Battle of Pusan Perimeter

The Battle of the Pusan Perimeter was the decisive defensive stand that prevented a North Korean conquest of South Korea in 1950.

Duration & Scope

1950 ongoing

< 1 year

Key Facts

Duration
August 4 – September 18, 1950 (46 days)
UN troop strength
140,000 troops
KPA troop strength
98,000 troops
Perimeter length
140 miles (230 km)
KPA major assaults
2 (August and September)

Strategic Narrative Overview

For six weeks, 140,000 UN troops held a 140-mile perimeter against 98,000 KPA soldiers who launched two major offensives in August and September. Fighting raged around Taegu, Masan, Pohang, and the Naktong River. UN control of the port allowed rapid reinforcement and supply, while UN naval and air superiority went unchallenged, gradually degrading KPA strength and logistics.

01 / The Origins

Following North Korea's invasion of South Korea in June 1950, the Korean People's Army drove UN and Republic of Korea forces steadily southward. Repeated defeats left UN forces with little territory remaining, ultimately compressed into a narrow defensive zone around the port of Busan in the southeastern tip of the Korean Peninsula, making a final coordinated stand unavoidable.

03 / The Outcome

The KPA, battered by attrition and supply failures, could not breach the perimeter. On September 15, 1950, UN forces executed the Inchon landing behind enemy lines, and UN perimeter forces broke out the following day. The KPA collapsed and retreated northward. The battle marked the farthest extent of North Korean advance; subsequent fighting eventually settled into a stalemate along roughly the original border.

Belligerents & Mobilization Analysis

Side A

1 belligerent

Korean People's Army (North Korea)
Peak Mobilized Forces~98K
Forces vs Casualties ratio
0Mobilized

Side B

3 belligerents

Republic of Korea Army (ROKA)United StatesUnited Kingdom
Outcome
UN defensive victory; KPA offensive halted and repulsed; UN forces broke out following the Inchon landing

Kinetic Engagement Axis

Major engagements timeline (1950–present)Timeline of major military engagements plotted chronologically.1950present1950Battle of TaeguSide B1950Battle of MasanSide B1950Battle of PohangSide B1950Battle of the Na…Side B

Scroll horizontally to view full axis. Events plotted relatively.

Side A victorySide B victoryInconclusiveDecisive / turning point

Location

Map of Busan, South KoreaMap of Busan, South KoreaBusan, South Korea