Battle of Inchon (1950): MacArthur's Amphibious Gamble in Korea

The Battle of Inchon was the amphibious landing by United Nations forces at the port of Inchon (now Incheon), on the west coast of South Korea, which began on 15 September 1950. Planned by General Douglas MacArthur under the code name Operation Chromite, it put a large force ashore far behind the North Korean army that had pinned UN troops into the south-east of the peninsula. Within two weeks Seoul had been recaptured and the course of the Korean War had been reversed.

Background: a war going badly

North Korea invaded South Korea on 25 June 1950. Its army, equipped with Soviet tanks and artillery, captured Seoul within three days and drove south. American troops rushed from occupation duty in Japan were outnumbered and forced to retreat alongside the South Korean army.

By early August the UN and South Korean forces held only a corner of the peninsula around the port of Pusan (Busan). In the battles of the Pusan Perimeter, General Walton Walker’s Eighth Army held a defensive line along the Naktong River against repeated North Korean attacks. The North Korean army, however, was now operating at the end of very long supply lines, nearly all of which passed through the road and rail hub of Seoul.

MacArthur had thought about an amphibious attack behind enemy lines from the first weeks of the war. He believed that a landing near Seoul would cut those supply lines, recapture the capital and trap the North Korean forces in the south between two UN armies.

Why Inchon was a gamble

Inchon was in many ways a very poor place for a landing. Its tides were among the most extreme in the world, with a range of around 10 metres. At low tide, wide mudflats stretched far out from the shore, so landing craft could reach the beaches only for a few hours around high tide. Suitable tides occurred only on a few days each month: 15 September, then around 11 October and early November.

The approach was through Flying Fish Channel, a narrow, twisting passage with strong currents that could easily have been mined. The small island of Wolmi-do, linked to the city by a causeway, guarded the harbour and had to be taken first, on the morning tide. The main landings would then follow on the evening tide, giving the defenders hours to react. The landing beaches were not open sand but the waterfront of a city, lined with seawalls that the troops would have to climb with ladders.

The US Joint Chiefs of Staff and senior Navy and Marine officers had serious doubts and suggested alternative sites further south, such as Kunsan. At a conference in Tokyo on 23 August 1950 MacArthur argued at length for Inchon. He contended that the very difficulties of the site meant the North Koreans would not expect an attack there, and that only a blow near Seoul could be decisive. The Joint Chiefs gave their approval later in the month.

Planning Operation Chromite

The landing force was X Corps, commanded by MacArthur’s chief of staff, Major General Edward Almond. Its core was the 1st Marine Division under Major General Oliver P. Smith, hastily assembled from units in the United States, the Mediterranean and the Pusan Perimeter. The US Army’s 7th Infantry Division, brought up to strength with thousands of South Korean recruits, and a regiment of South Korean marines were also assigned.

Naval forces, organised as Joint Task Force 7 under Vice Admiral Arthur Dewey Struble, numbered more than 200 ships, including American, British, Canadian, Australian, New Zealand, French and South Korean vessels. In total around 75,000 personnel took part in the operation.

Intelligence about the harbour was gathered by a small team led by US Navy Lieutenant Eugene Clark, who landed on islands in the approaches in early September. His group measured the mudflats and tides, gathered information from local people, and on the night of the landing lit the lighthouse on the island of Palmi-do to guide the fleet.

To mislead the enemy, UN forces carried out raids and bombardments at other points on the coast, including Kunsan. From 10 September aircraft attacked Wolmi-do with napalm, and from 13 September cruisers and destroyers bombarded the island and the shore batteries at close range, taking fire in return.

The landing on 15 September 1950

At 6:33 a.m. on 15 September the 3rd Battalion, 5th Marines, landed on Wolmi-do at Green Beach. Supported by tanks, the Marines secured the island within about two hours with very light losses, capturing or killing its North Korean garrison.

In the late afternoon, as the evening tide rose, the main assault went in. The 5th Marines landed at Red Beach, directly against the seawall of the city, while the 1st Marines landed at Blue Beach to the south. Troops scaled the seawalls with ladders under fire, in failing light and heavy smoke. At Red Beach First Lieutenant Baldomero Lopez was killed when he smothered a grenade with his body to protect his men; he was posthumously awarded the Medal of Honor. A photograph of him leading his platoon over the seawall minutes before his death became one of the best-known images of the war.

The North Korean garrison was small, estimated at a few thousand troops, many of them recent recruits. By midnight the Marines held the high ground overlooking the city. American losses on the first day were relatively light, around 20 killed and fewer than 200 wounded, far below what many planners had feared.

Pushing inland: 16 to 19 September

Over the next days the Marines cleared Inchon, with South Korean marines mopping up the city, and advanced east along the road to Seoul. On 17 September they destroyed a column of North Korean tanks and seized Kimpo Airfield, the best airfield in Korea, securing it the following day. Kimpo allowed land-based aircraft to support the advance. The 7th Infantry Division came ashore from 18 September and moved to protect the southern flank, while the Marines prepared to cross the Han River west of Seoul on 20 September.

On 16 September, as planned, the Eighth Army began its attack out of the Pusan Perimeter. The North Korean forces in the south, cut off from supplies and reinforcements, at first resisted strongly and then began to break apart.

The recapture of Seoul

The fight for Seoul was much harder than the landing. The North Koreans brought in reinforcements and defended the city street by street, behind barricades. Marines and soldiers fought through the city from 22 September, and much of it was destroyed by artillery, air strikes and fire.

On 26 September advancing units of the Eighth Army linked up with the 7th Infantry Division near Osan, south of Seoul. Almond had already declared the capital liberated on 25 September, although fighting continued until 28 September. On 29 September, in a ceremony in the damaged Capitol building, MacArthur formally returned the city to President Syngman Rhee.

Key people

• Douglas MacArthur (1880–1964), commander of UN forces, who conceived and championed the landing.
• Edward Almond (1892–1979), commander of X Corps.
• Oliver P. Smith (1893–1977), commander of the 1st Marine Division.
• Arthur Dewey Struble (1894–1983), commander of Joint Task Force 7.
• Baldomero Lopez (1925–1950), Marine officer killed on Red Beach and posthumously awarded the Medal of Honor.

Consequences

Inchon turned a looming defeat into a rout. Tens of thousands of North Korean soldiers were killed or captured during the campaign, and much of the North Korean army disintegrated as it fled north. Total UN casualties in the Inchon-Seoul campaign ran to several thousand killed and wounded, most of them in the battle for Seoul rather than at the beaches.

The success greatly increased MacArthur’s prestige and confidence. UN forces crossed the 38th parallel in early October and pushed toward the Chinese border. That advance provoked Chinese intervention, which led to the Battle of Chosin Reservoir and the long retreat of late 1950. MacArthur’s growing disputes with Washington ended with his dismissal by Truman in April 1951.

Inchon also entered military teaching. Staff colleges in many countries study it as an example of operational surprise and of the risks and rewards of amphibious warfare. In Incheon itself, a statue of MacArthur stands in Jayu Park overlooking the harbour, and a memorial hall commemorates the landing and the soldiers of the many nations who took part.

Timeline

• 1950, 25 June: North Korea invades South Korea.
• 1950, 23 August: MacArthur argues for the Inchon plan at a conference in Tokyo.
• 1950, 13 September: Warships begin close bombardment of Wolmi-do.
• 1950, 15 September, 6:33 a.m.: Marines land on Wolmi-do.
• 1950, 15 September, evening: Main landings at Red Beach and Blue Beach.
• 1950, 16 September: The Eighth Army attacks out of the Pusan Perimeter.
• 1950, 17–18 September: Marines capture and secure Kimpo Airfield.
• 1950, 26 September: UN forces from Inchon and Pusan link up near Osan.
• 1950, 29 September: MacArthur returns Seoul to President Syngman Rhee.

Why it matters

Inchon is often cited as one of the most daring amphibious operations in modern history. It saved South Korea from defeat in 1950, restored Seoul to its government and showed the power of sea-based forces, while the overconfidence it produced helped set the stage for the war’s next crisis.