Battle of the Pusan Perimeter (1950): Holding the Line in Korea

The Battle of the Pusan Perimeter was the six-week struggle in August and September 1950 in which United Nations and South Korean forces held a small corner of southeastern Korea against the North Korean army. After a summer of retreats, the defenders clung to a line around the port of Pusan (today Busan) while reinforcements arrived. Their stand made possible the Inchon landing and the turning of the tide in the Korean War.

Background: a summer of defeat

North Korea’s Korean People’s Army (KPA) invaded South Korea on 25 June 1950. Equipped with Soviet T-34/85 tanks and artillery, it captured Seoul within three days and drove south against a South Korean army that lacked tanks and anti-tank weapons. The United Nations Security Council, in the absence of the Soviet delegate, called on members to help repel the attack.

The first American units rushed from occupation duty in Japan were under-strength and poorly equipped. Task Force Smith was overrun near Osan on 5 July, and the US 24th Infantry Division lost Taejon in mid-July; its commander, Major General William F. Dean, was later captured. By late July, UN and South Korean (ROK) forces had been pushed into the southeast corner of the peninsula.

On 29 July Lieutenant General Walton H. Walker, commander of the US Eighth Army, issued his famous order that there would be no further retreat and that his troops must “stand or die”. In the first days of August his forces crossed to the east bank of the Naktong River and blew the bridges behind them.

The perimeter

The resulting line, roughly 140 miles (about 225 km) long, formed a rectangle around Pusan. The Naktong River covered most of the western side; rugged mountains formed the northern side, running east to the coast near P’ohang. The Korea Strait and the Sea of Japan protected the other two sides.

The perimeter had one great advantage: interior lines. Walker could move reserves by road and rail to whichever sector was threatened, while the North Koreans had to attack across rivers and hills at the end of long supply lines that American aircraft attacked constantly. The port of Pusan, only a short sea voyage from Japan, received a steady flow of men, tanks and ammunition.

The balance of strength shifted steadily during August. The US 2nd Infantry Division and the 1st Provisional Marine Brigade arrived from the United States, while tank battalions equipped with M26 Pershing and M4 Sherman tanks, and new 3.5-inch rocket launchers able to destroy the T-34, ended North Korea’s armoured advantage. South Korean divisions, badly mauled in July, were rebuilt with new recruits. UN aircraft dominated the skies, and North Korean forces increasingly had to move and attack at night.

What happened

From early August the KPA launched a series of attacks at several points at once. In the southwest, around Masan, US troops including the 25th Infantry Division fought back repeated assaults from early August until mid-September. In the centre, North Korean units crossed the river at the Naktong Bulge, a loop of the river west of Yongsan; the 24th Infantry Division and the newly arrived 1st Provisional Marine Brigade threw them back in heavy fighting between about 5 and 19 August.

The northern approach to Taegu, the provisional South Korean capital, saw some of the fiercest combat. In the valley known to Americans as the “Bowling Alley”, the US 27th Infantry Regiment and the ROK 1st Division under Paik Sun-yup stopped North Korean tank attacks in late August. On 16 August around 100 B-29 bombers carpet-bombed an area near Waegwan where enemy troops were thought to be massing, though the results were disputed. In the east, North Korean divisions advanced down the coast and briefly took P’ohang before ROK forces recovered it.

The war’s brutality was evident on both sides. On 17 August North Korean soldiers executed about 40 captured American soldiers on Hill 303 near Waegwan, one of several atrocities against prisoners in this period. Refugees crowded the roads, and fear of infiltrators led to tragic incidents involving civilians.

The decisive North Korean effort, often called the Great Naktong Offensive, began on the night of 31 August–1 September. Attacking along almost the whole line, the KPA came close to breakthroughs at the Naktong Bulge, near Taegu and in the east. Walker shifted his reserves from crisis to crisis, and the line bent but held. By mid-September the attackers were exhausted, short of food and ammunition, and heavily outnumbered.

Key people

Walton H. Walker commanded the Eighth Army and conducted a mobile defence that historians generally credit with saving the perimeter. Douglas MacArthur, commander of the UN Command, used the time won to plan an amphibious landing behind enemy lines. Paik Sun-yup, commander of the ROK 1st Division, became one of South Korea’s most respected soldiers. On the North Korean side, Kim Il-sung pressed for victory before American strength could grow, and Kim Chaek commanded the front.

Other UN contingents began to arrive during the battle. The British 27th Infantry Brigade landed at Pusan at the end of August, the first non-American ground troops of the UN Command apart from the South Koreans.

By the numbers

Breakout and consequences

On 15 September MacArthur landed US Marines and Army troops at Inchon, far behind North Korean lines, in the Battle of Inchon. The next day Walker’s forces began their breakout from the perimeter. Resistance was stubborn at first, but once the North Koreans realised their supply lines were cut, their army collapsed. On 26–27 September units from the perimeter linked up with forces advancing from Inchon near Osan, and Seoul was recaptured at the end of the month.

The success encouraged the UN Command to cross the 38th parallel and advance towards the Chinese border, a decision that brought China into the war in October and November 1950 and led to battles such as the Chosin Reservoir.

Legacy

The Pusan Perimeter is remembered in South Korea as the moment the republic came closest to extinction. Memorials stand along the Naktong at places such as Waegwan and Dabu-dong, and the UN Memorial Cemetery in Busan holds the graves of soldiers from many countries. Military historians often cite the battle as a classic example of a defence using interior lines and reserves.

Timeline

• 1950, 25 June: North Korea invades South Korea.
• 1950, 5 July: Task Force Smith is defeated near Osan.
• 1950, 29 July: Walker issues his “stand or die” order.
• 1950, early August: UN forces withdraw behind the Naktong River; the perimeter is formed.
• 1950, 5–19 August: First Battle of the Naktong Bulge.
• 1950, 16 August: B-29s carpet-bomb the area near Waegwan.
• 1950, 31 August–1 September: North Korea’s Great Naktong Offensive begins.
• 1950, 15 September: UN landing at Inchon.
• 1950, 16–18 September: Breakout from the perimeter begins.
• 1950, 26–27 September: Link-up with Inchon forces near Osan.

Why it matters

Had the perimeter fallen, the UN Command would probably have been driven from Korea in 1950. Its defence preserved South Korea as a state, gave MacArthur the chance to strike at Inchon and set the course of the war that followed.