Korean War Series: Operation Chromite: MacArthur’s Bold Plan for the Invasion of Incheon.

“As American forces were on the brink of being driven from South Korea by the invasion of the North Korean army, General MacArthur ordered an amphibious landing deep behind enemy lines. This reversed the Korean War virtually overnight.” James Mattis, from his book Call Sign Chaos: Learning to Lead.

The month of August was a tough one for the Allies encircled with their back to the sea around the port city of Pusan. Twice the North Korean People’s Army had penetrated the Pusan Perimeter at the Naktong River, and luckily for the Allies they weren’t able to meet their goal of destroying the defenders. While the defense of Pusan raged and the Allies lived on the brink of being shoved into the sea, Far East Commander Douglas MacArthur came up with a bold strategy to turn the tide of the war. His strategy, which was deemed reckless and impossible by other senior ranking officers, would land an amphibious invasion force behind North Korean lines at the port city of Incheon. His plan would put the invasion force close to the occupied South Korean capitol of Seoul, and would also sever the extremely stretched North Korean supply lines.

Map showing the overstretched North Korean lines, the Pusan Perimeter (blue section) and the Incheon Invasion (blue arrow). Photo Credit: ThoughtCo.com

What made the invasion seem reckless was the natural defenses of the Incheon beaches, which were basically rock-faced sea walls. Additionally, the tides at Incheon were extreme; rising and falling an average of 20 feet. This would mean that any initial force would be stranded and have to hold their position for hours until the evening tide came back in, allowing more ships to disembark reinforcements. MacArthur argued that this is why it was the best option for the assault; the North Koreans would not expect an attack there, when there were better options for the Allies elsewhere.

Incheon Invasion plan. Photo Credit: The History Reader.

There were three main objectives for Operation Chromite, as the invasion was called. First, securing the fortified island of Wolmi-do before securing the beach at Incheon. Then seizing the Kimpo airfield south of Seoul, then the capture of Seoul itself. In addition to his landings, the Eighth Army, which was holding its defense at Pusan, would simultaneously launch an offensive, giving the North Koreans no other option but to retreat. 

5th Marines holding the causeway on Wolmi-do island waiting for the tides to return for the follow on forces. Photo Credit: Korean War Online.

Starting on 13 September, two days of heavy bombardment on Wolmi-do island and Incheon proper prepped the area for the invasion force on the 15th. The 5th Marine Regiment assaulted Wolmi-do island at 0630 on the morning of the 15th. They met little resistance as they secured the island up to the causeway, partly due to the intensity of the naval and air bombardment, and also due to the element of surprise and misinformation from the Americans. The Marines secured the island by noon, and were forced to wait until late afternoon for the other elements to assault their objectives due to the receding tides. However, Allied air superiority for the surrounding 25 miles kept any chance of North Korean reinforcement from happening.

An infamous picture from the Incheon operation, 1st Lieutenant Baldomero Lopez leads his Marines over the sea wall. Photo Credit: Stars and Stripes.

The 1st Marines assaulted Red Beach at 5:33 p.m and secured the hill overlooking the beach 22 minutes later after a brutal but brief firefight. The landing force that assaulted the third beach, code named Blue Beach, hit at 5:22 pm, and this force took its objectives by 1:30 am on the 16th. By 7:30 am on the 16th, the entire landing force had made contact with each other, and secured a solid line around the city of Incheon itself, sealing the fate of what was left for defenders in the city. The US Army 7th Infantry Division would follow on and relieve the elements of the 1st Marine Division.

By the evening of the 16th, the invasion force controlled the high ground east of Incheon and set a strong launching point for their next objective; taking the airfield at Kimpo. All told, the X Corp, which the unit was designated once the 1st Marine Division and the US Army 7th Infantry Division were all ashore, suffered 224 men killed and 809 wounded in both the landings at the beachhead as well as the fight in the city of Incheon itself. The North Korean People’s Army lost an estimated 1,350 men killed in action.

The Assault on Kimpo Airfield.

On 17 September 1950, the 2nd Battalion of the 5th Marine Regiment set out to secure the Kimpo Airfield. They secured the airfield, which was fortunately left intact by the fleeing North Koreans who did not have time to do damage to the runways and other infrastructure there. The North Koreans attempted a counter attack to retake the airfield that evening but they were repelled by the Marines.

The Incheon landing was a big gamble that paid off for General MacArthur and the Allies. With the Eighth Army breaking out of Pusan the North Korean high command had no choice but to begin to withdraw. Their supply lines had been cut by the invasion at Incheon, and they risked having their entire force crushed by both the X Corps and also the Eighth Army. The North Koreans fell back across the Han river and began to make preparations to hold the South Korean Capitol of Seoul. The X Corp began to advance to positions outside of Seoul starting on 18 September. While Incheon would be a quick victory for MacArthur, Seoul would prove to be a much tougher nut to crack. But that will have to wait until next time.


Gamel, Kim. ‘This reversed the Korean War virtually overnight’: The Incheon landing’s victorious, bloody legacy 69 years later. Stars and Stripes. 10 September 2019. https://www.stripes.com/news/pacific/this-reversed-the-korean-war-virtually-overnight-the-incheon-landing-s-victorious-bloody-legacy-69-years-later-1.598150

Memory Bank Changing the Game at Incheon. Korean War Legacy Foundation. 2020 https://koreanwarlegacy.org/chapters/changing-the-game-at-incheon/

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