Here's What You Need to Know: The battle for Seoul proved to be a relatively brief but exceedingly tough fight.
On September 15, 1950, the United Nations X Corps, spearheaded by two regiments of the U.S. 1st Marine Division, landed at Inchon, on South Korea’s west coast, 25 miles from the capital of Seoul. The landing was a spectacular gamble by UN Supreme Commander Douglas MacArthur and proved to be an equally spectacular success. Despite rampant rumors of an imminent landing circulating for weeks before the actual event, MacArthur’s Inchon assault completely surprised the North Koreans, whose army was largely engaged in attacking UN forces along the Pusan Perimeter, far to the south. Inchon proved to be only lightly defended by the North Korean People’s Army (NKPA), and the U.S. Marines rapidly established a beachhead. The battle for Inchon was quickly over. The next objective was Seoul itself. The capital would prove a much tougher nut to crack.
To Take Back Seoul
War had begun on the Korean Peninsula on June 25, 1950, when North Korean Russian-made T-34 tanks crashed across the 38th parallel and rapidly routed the defending Republic of Korea (ROK) forces. Within days, Seoul had fallen to the North Koreans and the bridges across the Han River had been blown by the retreating ROK Army. American President Harry Truman reacted immediately and forcefully to counter the naked Communist aggression, rushing the U.S. 24th Infantry Division to Korea from occupation duty in Japan to help stem the onrushing Communist tide. At the same time, the United Nations, with the Soviet Union absent in protest of Nationalist China’s presence on the Security Council, voted to enter the war on South Korea’s side.
Undeterred by international sanctions, the North Korean forces continued their drive southward, hemming in the UN forces around Pusan, in the extreme southeast of the country. MacArthur struck back with his audacious amphibious assault at Inchon. American Admiral William F. “Bull” Halsey spoke for many when he described MacArthur’s counterattack as “characteristic and magnificent. The Inchon landing is the most masterly and audacious strategic stroke in all history.” Other military leaders called it nothing less than “a 20th century Cannae.” (In 216 bc, Carthaginian leader Hannibal inflicted Imperial Rome’s greatest defeat at Cannae, on the Adriatic coast.)
The surprise landing immediately threatened the North Koreans’ line of communication to the Pusan Perimeter, requiring a pullback of NKPA units from the south to avoid the risk of having them permanently cut off. The capital of Seoul was itself not initially occupied by many North Korean troops, but this would quickly change. As a result of the Inchon landing, the North Koreans sent reinforcements into the greater Seoul area, intending to make a determined stand in the capital. UN forces advancing from the seaport of Inchon would have to battle 20,000 NKPA troops tasked with holding Seoul. They would prove stout adversaries.
MacArthur reasoned that the recapture of Seoul was a crucial follow-up to the Inchon landing. “By seizing Seoul, I would completely paralyze the enemy’s supply system coming and going,” the general noted. “This in turn would paralyze the fighting power of the troops that now faced [Lt. Gen. Walton H.] Walker. Without munitions and food they would soon be helpless and disorganized, and could be easily overpowered by our smaller but well supplied forces.”
At the beginning of the war, Seoul had a population of nearly two million people. The city core was surrounded by hills, cottages, and rural villages, but the inner city contained modern office buildings that were solidly constructed and maintained. Wide thoroughfares crisscrossed the city. One major road, Ma Po Boulevard, was lined on both sides by two- and three-story stucco and masonry structures as well as churches, hospitals, and walled compounds. Seoul was a logistical hub for the North Korean invaders because the vast majority of their supplies were funneled through a fairly narrow corridor in and around the South Korean capital.
September 18: The Drive to Seoul Begins
X Corps, commanded by MacArthur’s erstwhile chief of staff, Maj. Gen. Edward M. Almond, began its drive from Inchon to Seoul on September 18. The 5th Marines, under Lt. Col. Raymond L. Murray, advanced on Kimpo Airfield, Seoul’s primary airport, and captured it with little difficulty. Kimpo lay some miles south of the Han River (Seoul is on the river’s north bank). Troops and supplies were flown into Kimpo while the Marines continued to advance cautiously eastward.
The newly arrived 7th Marines covered the 5th Marines’ northwestern flank between Seoul and Uijongbu, while the U.S. Army’s 31st Infantry, on the X Corps southeastern flank, advanced to make contact with Walker’s units moving up from the Pusan Perimeter. The 187th Airborne also landed at newly liberated Kimpo in late September to provide additional flank protection to the Marines south of the Han.
North Korean units called to defend Seoul included the green 18th Division, which initially had been heading to the Pusan Perimeter, and an experienced regiment of the 9th Division, which had been fighting along the perimeter’s Naktong River line. In addition, roughly 2,000 troops of the 78th Independent Infantry Regiment and the 25th Brigade moved into the Seoul area as rapidly as possible after the Inchon landing on express orders from North Korean dictator Kim Il Sung. Other Communist units in the Seoul area were the 70th Regiment, the 42nd Tank Regiment, and the 107th Security Regiment.
The 7th Marines were still en route to Inchon when Maj. Gen. Oliver P. Smith’s 1st and 5th Marines began their push from the seaport to the capital. Colonel Lewis B. “Chesty” Puller’s 1st Marines pressed forward along the Seoul-Inchon highway, heading directly for Yongdungpo. The 5th Marines, on Puller’s left, managed to fully secure Kimpo Airfield by September 19 in preparation for crossing the Han River to the west of Seoul. Opposition was light in the first days after the Inchon landing because the NKPA was still consolidating its units in the Seoul area. The Communist forces hoped to use natural obstacles such as the river and the hills ringing the city to retain control of the capital. The U.S. Army’s 7th Division had begun disembarking at Inchon on September 18, and South Korean units joined the campaign. They would all be needed, as NKPA resistance rapidly stiffened around Seoul.
On September 18, Almond ordered Smith to send his units across the Han and capture a hill position north of the capital. Smith issued his own order to his regiments. On the 19th, they were to secure a Han crossing site near Haengju, followed by a river crossing on the 20th and the capture of the Communists’ mountain fortress, Hill 125. At 8:40 on the evening of the 19th, a scouting party of 14 men from the 5th Marines’ Reconnaissance Company swam the river to locate a suitable crossing site for the regiment on the north bank. They landed safely at the Haengju ferry site and reconnoitered, finding no enemy in the immediate vicinity.
North Korean troops, in fact, were ensconced on Hill 125, and after amphibious tractors (LVTs) carrying the rest of the company were halfway across the river, heavy enemy fire crashed down on them, forcing them to retreat to the south bank. A daylight crossing of the river was now required. The Marines began a heavy predawn bombardment of Hill 125, followed by an assault crossing at 6:45 am led by I Company of the 3rd Battalion, 5th Marines. Within three hours, they secured Hill 125, and the rest of the 3rd Battalion crossed in LVTs without incident.
By nightfall, the 5th Marines, along with the 2nd Battalion of the ROK 1st Marine Regiment and an attached U.S. tank company, were on the north bank of the Han. The tanks had been ferried across by a combat engineer battalion using pontoon bridging. Hill 125 was just eight miles from downtown Seoul. The 5th Marines’ eastward advance continued, this time north of the river.
The Battle for Yongdungpo
Also on the morning of September 20, Puller’s 1st Marines closed on the Seoul suburb of Yongdungpo. The Marines repulsed a counterattack by five T-34s, and the NKPA 87th Regiment of the 18th Division lost 300 troops and several tanks. Puller’s forces moved directly along the highway and through hill country south of the Han. The Communists withdrew into Yongdungpo itself. Puller requested unrestricted fire support from Marine artillery and airplanes. Almond granted Puller’s request.
At 6:30 am on September 21, Puller launched his attack into Yongdungpo. Staff Sergeant Lee Bergee of the 2nd Battalion, 1st Marines, recalled the assault. “Yongdungpo was surrounded by a moat on one side, by a wide rice paddy on the west, and by high ridges on the southeast,” said Bergee. “Staring at the sooty chimneys of the city, I wondered how many of us would be killed taking this dirty town. Yongdungpo was literally infested with North Korean troops. All afternoon we observed them fortifying their ridge. Artillery, heavy mortars, and our Corsairs pummeled Yongdungpo that afternoon. The 4.2s [mortars] fired white phosphorous, setting sections of the city ablaze. One of our planes dropped napalm on a block-long fuel dump. Flame and smoke rose a mile and a half into the air.”