Battle of Inchon

• 1. Introduction

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  The Battle of Inchon began on the 15th of September 1950, when United States Marines waded ashore onto a stretch of Korean coastline that nearly every senior military officer had declared impossible to attack. The harbor at Incheon had tides swinging 29 feet on an average day, narrow channels that could be sealed with a handful of mines, and seawalls too tall for men to simply climb over. US Navy Commander Arlie G. Capps summed it up plainly: the harbor had "every natural and geographic handicap." And yet, within a single day, the city fell. The operation involved some 75,000 troops and 261 naval vessels, and it would produce one of the most dramatic strategic reversals of the entire Korean War. How did a plan so widely opposed reach the battlefield? What made the tides, the seawalls, and the surprise work in the attackers' favor? And what did the victory actually cost when the fighting moved from the harbor toward Seoul?

• 2. The Desperate Summer

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  On the 25th of June 1950, North Korean forces crossed into South Korea, and the Korean People's Army drove south with a speed that shocked the United Nations forces sent to stop them. The KPA exploited a consistent tactic: frontal assault combined with double envelopment on both flanks, surrounding defending units and forcing them into disorganized retreat. By August, UN and Republic of Korea forces had been compressed into a narrow defensive zone in the southeastern corner of the peninsula, known as the Pusan Perimeter.

  When the KPA approached the Pusan Perimeter on the 5th of August, they tried the same frontal assault technique on the four main avenues of approach. The resulting battles at Masan, at the Naktong Bulge, at Taegu, and along the east coast at P'ohang-dong were brutal. For the first time in the war, North Korean tactics failed. The KPA attacks stalled.

  By the end of August the KPA had been pushed well beyond their limits. Many of their original units were at far reduced strength, and shortages of food, weapons, and replacement soldiers proved devastating. On the 1st of September, they gambled everything on one final five-pronged assault across the entire perimeter: the Great Naktong Offensive. KPA troops surrounded Taegu, recrossed the Naktong Bulge, and threatened multiple sectors simultaneously. Despite this effort, in some of the most brutal fighting of the war, they could not hold their gains. The KPA retreated from the offensive a much weaker force, and newly vulnerable to a counterattack that was already being planned far away in Tokyo.

• 3. MacArthur's Gamble

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  General of the Army Douglas MacArthur conceived of an amphibious landing behind KPA lines within days of the war's outbreak. Seoul had fallen in the first days of fighting, and MacArthur believed that only a decisive stroke far from the Pusan fighting could turn the tide. He preferred Incheon as the landing site over Chumunjin-up or Kunsan, even though Incheon's defenses were the most formidable of the three options.

  His first plan, code-named Operation Bluehearts, called for the US Army's 1st Cavalry Division to land at Incheon on the 22nd of July. By the 10th of July that plan was abandoned, as the 1st Cavalry Division was urgently needed at the Pusan Perimeter. On the 23rd of July, MacArthur formulated a new plan, code-named Operation Chromite, built around the 2nd Infantry Division and the 5th Marine Regiment. That plan also collapsed when both units were pulled south to Pusan. MacArthur turned to the 7th Infantry Division, his last reserve in East Asia.

  To command the landing forces, MacArthur activated X Corps and appointed Major General Edward Almond, his own chief of staff, as its commander. Rebuilding the force for the operation was an enormous logistical challenge. The 7th Infantry Division had already sent 9,000 of its men to reinforce Pusan and was badly understrength. The Marine Corps, reduced in size after World War II, had to reconstitute the 1st Marine Division by pulling units from as far away as the Mediterranean Sea. MacArthur also assigned Korean Augmentation To the United States Army troops, ROK conscripts integrated directly into US Army units, to fill the 7th Infantry Division's gaps.

  US Navy leaders favored a landing at Kunsan, closer to the Pusan front and the KPA's main supply axis through Taejon. MacArthur rejected the idea, arguing a landing there would merely place more troops in a larger Pusan pocket rather than delivering a truly decisive blow. He believed that because Incheon's conditions seemed so inhospitable, the KPA would never expect an attack there.

• 4. The Tokyo Briefing

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  On the 23rd of August 1950, the most consequential military meeting of the Korean War took place at MacArthur's headquarters in Tokyo. Chief of Staff of the United States Army General Joseph Lawton Collins, Chief of Naval Operations Admiral Forrest Sherman, and USAF operations deputy Lieutenant General Idwal H. Edward all flew from Washington, D.C., to Japan to attend. General Hoyt Vandenberg, Chief of Staff of the Air Force, did not attend, possibly, as one account notes, because he "did not want to legitimize an operation that essentially belonged to the Navy and the Marines."

  The Marine Corps staff, who would actually lead the landings, were not invited to the briefing. That exclusion became a lasting source of grievance. Nine members of Admiral James H. Doyle's staff spoke for nearly 90 minutes on every technical and military challenge the operation would face. The channels could be blocked by mines, the tides could prevent follow-on landings, and the anchorage was too small. The word "impossible" ran through the room.

  MacArthur waited until they finished, then spent 45 minutes making his case. He argued that Incheon's apparent impregnability was itself an advantage: the North Koreans would not defend what they believed could not be attacked. He told the assembled officers that victory at Incheon would spare the UN a brutal winter campaign and sever KPA supply lines across South Korea. He won over Admiral Sherman partly through an unexpected appeal, recounting how the US Navy had carried him out of Corregidor to safety in 1942. Sherman agreed to back the operation. Doyle, who had just spent 90 minutes cataloguing the reasons for failure, was furious.

  The Joint Chiefs of Staff approved the plan on the 28th of August. President Truman also gave his approval. The operation that almost no one in the room had initially supported was now official.

• 5. Intelligence and Deception

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  Maintaining the element of surprise posed a particular problem in the weeks before the landing. The press in Japan was already calling the approaching operation "Operation Common Knowledge," and a North Korean-Japanese spy arrested in Japan in early September 1950 was found carrying a copy of the actual plan. UN commanders did not know whether he had transmitted its contents to Pyongyang before his capture.

  To draw North Korean attention south, toward Kunsan, the UN ran an elaborate deception campaign. On the 5th of September, the USAF's Far East Air Forces began attacking roads and bridges near Kunsan, the kind of raids expected before an invasion. A naval bombardment of Kunsan followed on the 6th of September. On the 11th of September, B-29 Superfortress bombers joined the campaign, striking military installations in the area. USMC officers on the docks at Pusan briefed their men on a Kunsan landing within earshot of Korean bystanders. On the night of the 12th to the 13th of September, a Royal Navy frigate landed US Army special operations troops and Royal Marine Commandos on the Kunsan docks, making certain North Korean forces noticed.

  At the same time, a small intelligence team was operating deep inside the harbor MacArthur actually intended to attack. US Navy Lieutenant Eugene F. Clark led a reconnaissance team that had landed on Yonghung-do, an island in the mouth of Incheon harbor. Clark's team worked with local civilians to measure tides, map beach composition, locate mudflats and seawalls, and chart KPA artillery positions on the island of Wolmi-do. Clark observed the Incheon tides for two weeks. He found that American tidal charts were inaccurate, but that Japanese charts were quite good. He also reported something critical: the North Koreans had not systematically mined the channels.

  When the KPA discovered Clark's team, they attacked Yonghung-do with six junks. Clark mounted a machine gun on a sampan and sank them. The KPA killed perhaps as many as 50 civilians in retaliation for helping the team. Clark's team held on. At 00:50 on the 15th of September, Clark and his South Korean squad activated the lighthouse on the island of Palmido, lighting the path for the invasion fleet moving through Flying Fish Channel.

• 6. Green, Red, and Blue

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  At 06:30 on the 15th of September 1950, the 3rd Battalion, 5th Marines, led by Lieutenant Colonel Robert Taplett, hit Green Beach on the northern side of Wolmi-do with nine M26 Pershing tanks from the 1st Tank Battalion. One tank carried a flamethrower; two others had bulldozer blades fitted to their hulls. The KPA defenders were outnumbered by more than six to one. By noon the entire island was secured at a cost of just 14 casualties. KPA losses included over 200 killed and 136 captured, drawn primarily from the 918th Artillery Regiment and the 226th Independent Marine Regiment.

  The tide then receded, stranding the Marines on Wolmi-do until evening, when it rose high enough to allow the main landings at Red and Blue Beaches. At 17:24, the first wave of the 5th Marines' 1st and 2nd Battalions crossed the line of departure toward Red Beach, using ladders to scale the seawalls. Lieutenant Colonel Raymond L. Murray's mission was to seize an area 3,000 yards long and 1,000 yards deep, covering Cemetery Hill, Observatory Hill, and the Inner Tidal Basin. Three of the eight LSTs supporting the landing took hits from mortar and machine gun fire from KPA defenders on Cemetery Hill, killing a sailor and wounding several others.

  Four miles to the southeast, Lewis "Chesty" Puller's 1st Marine Regiment came ashore at Blue Beach, where 2.5 miles of mudflats forced the use of 172 Amtracs. Two Landing Ship Medium Rockets each fired 2,000 5-inch rockets to suppress the beach ahead of them. By 21:50 that night, the 1st and 2nd Battalions of the 11th Marines' artillery were in position on the beachhead and ready to support the advance inland.

  The following morning, General Oliver P. Smith's 1st Marine Division had its orders. Six T-34 tanks moving west toward Incheon were caught near the village of Kansong-ni; a strike of eight Marine F4U Corsairs from VMF-214 destroyed two and drove off the rest, while M26 Pershing tanks finished three more. The push toward Seoul had begun.

• 7. Kimpo and the Road to Seoul

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  Kimpo airfield was the largest in Korea, and MacArthur demanded its capture early in the operation. On the 17th of September, the 5th Marines' 2nd Battalion reached the airfield's edge by 18:00 and seized the southern portion within two hours. The 400-500 KPA soldiers defending it appeared surprised; they had not even mined the runway. Several North Korean aircraft were still parked on the field, including a Yak-3 and two Stormoviks. The Yak-3 was later flown to Japan for USAF technical evaluation. US engineers repaired the local railroad on the 19th of September, running 8 miles inland, and transport planes began flying in fuel and ordnance. By the 22nd of September, the Marines had unloaded 6,629 vehicles, 53,882 troops, and 25,512 tons of supplies through the beachhead.

  The advance on Seoul itself was a different kind of fight entirely. Before the battle, North Korea had just one understrength division inside the city. X Corps commander Almond assumed operational command on the 21st of September, determined to declare Seoul liberated by the 25th: exactly three months after the North Korean assault across the 38th Parallel. The 5th Marines had entered the city on the 20th of September, but the house-to-house combat proved slow and costly. Almond declared Seoul liberated on the evening of the 25th; MacArthur repeated the claim the following day. At the time of both declarations, US Marines were still fighting in most of the city. The last KPA elements were not driven out or destroyed until the 28th of September.

  While the fight for Seoul ground on, Walton H. Walker's Eighth Army broke out of the Pusan Perimeter on the 16th of September. By the 22nd of September the KPA forces around the perimeter were in full retreat, and a full counteroffensive began on the 23rd. Of the 70,000 KPA troops around Pusan, between 36,000 and 41,000 had been killed or captured in the fighting from the 1st to the 15th of September. Approximately 30,000 managed to escape north and were later reconstituted as the cadre for new KPA divisions, re-equipped by the Soviet Union. The UN assault pushed into North Korea on the 30th of September.

• 8. Verdict

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  Military historian Spencer C. Tucker called the Incheon landings "a brilliant success, almost flawlessly executed" and described the operation as the only unambiguously successful large-scale US combat operation for the next 40 years. Other commentators called it MacArthur's "greatest success" and "an example of brilliant generalship and military genius."

  Not every assessment was unqualified. Russell Stolfi argued that while the landing itself was a strategic masterpiece, the subsequent 11-day advance on Seoul, covering only 20 miles, largely negated it. Stolfi contrasted this with German forces in the Baltic in 1941, who achieved strategic surprise and then advanced nearly 200 miles in four days. The American advance, he contended, was characterized by cautious orders, concerns about phase lines, limited reconnaissance, and command posts kept well behind the front line. The German approach relied on forward leadership, oral orders, flexible combat groupings, and vigorous reconnaissance.

  The numbers after the battle speak to the scope of the strategic reversal. Within a month of the Inchon landing, American forces had taken 135,000 KPA troops prisoner. The operation had involved some 75,000 troops and 261 naval vessels and had led to the recapture of Seoul two weeks after the first Marines stepped ashore. The film Inchon, released in 1981 and directed by Terence Young, cast Laurence Olivier as MacArthur; a 2016 South Korean production, Operation Chromite, directed by John H. Lee, starred Liam Neeson in the same role. The battle that nearly every senior officer had called impossible had become, by the measure of its outcome if not its follow-through, one of the most studied amphibious operations in modern warfare.