In the morning of June 25, 1950 Gen MacArthur flew from Tokyo into Suwon Airfield 15 miles south of Seoul. There he was met by President Syngman Rhee, the ROK minister of defense who doubled as prime minister, the US ambassador, and US advisors to the ROKA. Borrowing a car, MacArthur’s entourage drove north to a point overlooking the as yet to be blown railroad bridge crossing the Han River out of Seoul. The capital was burning, artillery rounds were bursting on its north side, and the roads full of thousands of refugees. The remnants of the retreating ROK 1st, 7th, and Capital divisions were fleeing the city as the 3d and 4th NK Divisions lunged in from the north; the 6th NK Division headed for Inch’on. It was here MacArthur made the decision to turn the tide and request authority to commit ground troops and air support from President Truman. He already had a plan in mind, and it required an amphibious landing in the enemy’s rear.
MacArthur is often credited as conceiving the Inch’on landing, but the true author is Donald McB. Curtis, a Pentagon staff member who prepared contingency plan SL-17 on June 19, by coincidence just days before the NK invasion. The plan presupposed an NK invasion, a retreat south, establishment of a perimeter at Pusan, and an outflanking amphibious landing to support a counteroffensive once Pusan was reinforced. MacArthur’s General Headquarters (GHQ) requested copies within days of the invasion. MacArthur may not have been the author, but it was his drive and vision that saw its implementation, and of course his staff that accomplished the expanded planning to make it happen.
Here a marine 155mm M1A1 howitzer is towed by a dozer-tractor off a pontoon raft. Both marine and army divisions had one “155” battalion, and two battalions were assigned to X Corps, one being self-propelled. (USMC)
Army commanders. The 32d Infantry was the principal army unit to participate in the campaign. From left to right: Col Charles E. Beauchamp (32d Infantry), MajGen David G. Barr (7th InfDiv), MajGen Edward M. Almond (X Corps), and Marine BGen Edward A. Craig (Assistant Division Commander, 1st MarDiv). (USA)
A marine M26 Pershing heavy tank, nicknamed “Fightin’ Fool,” drives off an LST ramp at the base of a sea wall as the tide recedes. C-rations for a week are secured to the vehicle. (USMC)
MacArthur’s chief of staff, MajGen Edward M. Almond and his GHQ staff quickly developed an initial plan, Operation Bluehearts. Bluehearts envisioned the 24th InfDiv deploying to Pusan from Japan and driving north to Suwon to block the NK advance. It was assumed Seoul could not be held. It would be followed by the 25th InfDiv, which would position itself in the central portion of the peninsula and back up the faltering ROKA. On about July 20 an amphibious assault at Inch’on would be conducted by a hoped-for marine RCT and the 1st CavDiv to cut the NK supply line. This plan was discussed on July 4 at GHQ in Tokyo with marine representatives present. While a sound plan, it was impossible to accomplish with the available under-strength and ill-trained divisions. The NK were moving too fast and the ROKA crumbling at a proportionate rate. Of course the defeat of Task Force Smith the next day dashed any hopes of executing Bluehearts as conceived. Still the 1st CavDiv rushed to embark, expecting the plan to be carried out. Instead, Bluehearts turned into an amphibious reinforcement landing at Po’hang-dong 70 miles north of Pusan. The landing was unopposed, although the NK were closing in. Po’hang was chosen as port faculties at Pusan were overly congested. While a much smaller operation, Bluehearts offered navy amphibious forces a much-needed shakedown before the more challenging Inch’on landing.
Four LSTs beached at Beach Red discharge their cargo. Supply dumps can be seen to the left. Inch’on was the only US amphibious operation in which a major operational port was secured on D-Day, a factor contributing to the operation’s success. (USMC)
Even though Bluehearts evolved into something different, MacArthur recognized the need to cut the NK supply line and establish a force in their rear to support the Pusan breakout. It would also hurt the NK psychologically and materially as well as force them to fight on two widely separated fronts. Reestablishing Seoul as the capital only three months after the NK invasion would be a significant political victory. Inch’on was Korea’s second largest port (the first being Pusan) and Kimpo Airfield was the best on the peninsula.
The Inch’on landing has been characterized as brilliant, daring, and extraordinary. It was certainly daring as the forces involved were so hastily assembled, under-trained, and lacking in rehearsal – extensive practicing and dry-runs had long been deemed essential for any amphibious operation. It was also bold because of the dangerous approach channel that was negotiated at night, the tidal hazards, and the confinement of the invasion fleet in such a small maneuver area. The doctrine of landing an amphibious force deep in the enemy’s rear, especially when the friendly force dominates the sea and sky, was well established and not without precedent. The Allied landings at Anzio and Salerno, Italy in 1944, both on the west coast of a peninsula, had been equally risky for their own reasons, but successful.
MacArthur’s staff continued to develop flanking landing plans. Operation Plan 100-B for Inch’on, 100-C for Kunsan on the west coast some 100 miles from Korea’s southwest tip and less than halfway up the coast toward Inch’on, and 100-D at Chumunjin-up on the east coast just south of the 38th Parallel. Kunsan was not far enough behind the enemy’s rear and the landing force could too soon meet enemy troops withdrawing from Pusan. It still left much of the NK line of communications intact. While secondary supply lines served the east coast, the Chumunjin-up course of action would not sever the main line through Seoul unless the landing force fought all the way across the peninsula. Some recommended it as they feared the hazards of the Inch’on basin, but it would have required a two-division force (with its own lengthy and vulnerable supply line) to traverse 160 miles, exposing their flanks to withdrawing enemy divisions.
The early capture of Kimpo Airfield would not only provide a base for close air support fighters, but also for resupply and medical evacuation. Here an R4C (C-47) of Marine Transport Squadron 152 offloads fuel at Kimpo. (USMC)
For an amphibious assault of this magnitude, a 160-day planning phase was recommended; GHQ planners had 34. MacArthur issued Operation Plan 100-B for Inch’on on August 12 (D-34). He did not provide a copy to the JCS although they knew that it was underway. The National Defense Act, which outlined the relationship between the JCS and theater commanders-in-chief was nebulous, and MacArthur opted to keep things in close-hold. Two days previously the JCS had briefed President Truman that while a marine division was en route to Korea, they did not feel a landing at Inch’on was a viable course of action. FECOM pressed on with plans for the landing and the Pusan breakout.
On August 23 (D-23) a top level conference was held at FECOM headquarters in Tokyo, attended by MacArthur, Gen J. Lawton Collins (Army Chief of Staff), Adm Forrest P. Sherman (Chief of Naval Operations), ViceAdm C. Turner Joy (Naval Forces, Far East), LtGen Lemuel C. Sheperd, Jr. (Fleet Marine Force, Pacific), MajGen Edward M. Almond (FECOM Chief of Staff), MajGen Oliver P. Smith (1st MarDiv), MajGen David G. Barr (7th InfDiv), and RearAdm James H. Doyle (Attack Force Commander). The day before, MacArthur had informed MajGen Smith that his division would spearhead the Inch’on landing, which was the first Smith had heard of such a plan. Reflecting Doyle’s concerns with the Inch’on tides and the treacherous channel, Smith suggested that a better landing site might be Posung-Myun just south of Inch’on. Almond dismissed this option. Oddly, neither Smith nor Sheperd were invited to the Tokyo meeting, but MajGen Barr, the follow-on division commander, was.
A marine DUKW-353 or “Duck” 2½-ton amphibious truck crawls across the Inch’on mud flats. Saplings have been laid as a corduroy road on which wire mesh matting is laid using a special rack. (USMC)
MacArthur was adamant that the landing would be at Inch’on. The navy’s objections regarding tides, terrain, and other physical handicaps such as Wolmi-do which they feared was heavily fortified and dominated the landing beaches, were brushed aside. The navy also recommended a three- to four-day preparatory bombardment, but the FECOM staff felt such a long bombardment would eliminate tactical surprise and allow the North Koreans to shift forces to meet the landing. MacArthur felt that the recapture of Seoul would save 100,000 lives and lead to a quick end for the war, which he expected to be over by Christmas. He closed with, “We shall land at Inch’on and I shall defeat the enemy.”
The navy and marines made a last effort to convince MacArthur to land at Posung-Myun, but it was dismissed. MacArthur’s mind was fixed on the immediate seizure of a port to sustain the force. At the end of the meeting Doyle made the comment, “General, I have not been asked nor have I volunteered my opinion about this landing. If I were asked, however, the best I can say is Inch’on is not impossible.” The navy was not the only concerned party: Gen Collins, too, held reservations regarding enemy strength and capabilities at Inch’on, which had been barely addressed. He also questioned whether Eighth Army could break out and link up on a timely basis and only received reassurances backed by no facts. MajGen Barr made a somewhat positive observation, “It’s so wrong that it’s right. The element of surprise will be great.” Some gave it a 5,000-to-1 chance of success. MacArthur was completely confident.
Another MacArthurian blow to the marines followed when he informed LtGen Sheperd that MajGen Almond had been promised command of the as-yet-to-be-activated X Corps, the landing force. With extensive amphibious expertise, Sheperd had hoped for the command; Almond had none.
Gen Walker, commanding Eighth Army, proposed an alternative plan to Gen Collins, Army Chief of Staff. Radio intercepts indicated that the NK were going to throw every remaining unit at the perimeter in desperate hope of defeating tottering UN forces. It was known that the bulk of the forces would attack the west side of the Naktong River, mostly defended by Americans. Once the initial attacks had spent themselves Walker proposed to conduct limited objective attacks to drive the enemy to the west, as well as probing attacks by the ROKA in the north to push the NK into the mountains and away from the perimeter. A main attack would be launched northwest toward Taejon on the NK supply line and at the same time an amphibious assault conducted at Kunsan. This force, besides cutting a main coastal road and securing a secondary harbor, would attack northeast to Taejon. It was hoped that a large portion of the NK that had survived the attacks on the Naktong front would be enveloped and trapped in southwest Korea. While Collins liked the plan, MacArthur’s dramatics swayed the JCS to let him have his way, although it is apparent that some thought he would choose another course of action.
On August 24 (D-22) Far East Air Force began planning the allocation of air support to both the upcoming landing and to reinforce Eighth Army’s breakout. On the 26th (D-20) MacArthur announced Almond’s assignment as X Corps commander upon activation of the corps in Tokyo. That same day Gen Omar N. Bradley, Chairman of the JCS, briefed President Truman on what Gen Collins and Adm Sherman had learned of the Inch’on plan at the August 23 conference. They had not been asked to approve the plan nor was MacArthur obligated to ask them to do so. While the service chiefs had reservations, Truman was optimistic. The JCS gave its conditional approval on August 28 (D-18) for a landing at Inch’on or a beach to the south, indicating they were not comfortable with the former. They required MacArthur to keep them abreast of changes and recommended that an alternative plan be developed for Kunsan.
On August 30 Commander, Naval Forces, Far East assigned Joint Task Force 7 (JTF7) to conduct the Inch’on landing. JTF7 was not activated until September 11 (D-4). The various naval task forces transporting and supporting the landing force would depart from four ports in Japan and Korea between September 5 and 13. Preliminary aerial bombardment of Wolmi-do and Inch’on would commence on September 10 (D-5) with naval shelling on the 13th (D-2).
X Corps Operation Order 1 was issued on August 28 (D-18) and received by 1st MarDiv on the 30th. The division, though, had received a preliminary briefing on August 19 (D-27) and commenced planning. Not only was this the shortest planning time ever allotted for a divisional amphibious assault, but only a quarter of the staff was aboard the USS Mount McKinley (AGC-7) to undertake the myriad of planning tasks. The division issued Operation Order 2-50 on September 4 (D-11). Planning time was so short that, contrary to normal practice, the division wrote detailed landing plans for the regiments rather than the regiments and battalions preparing their own after receiving the higher echelon’s order.
Ships of the JTF7 Transport Group take up position in the transport area outside Inch’on Harbor. (USN)
The X Corps operation plan had begun to be developed by the GHQ Joint Strategic Plans and Operations Group in July. It was taken over by the GHQ Special Planning Staff (aka “Force X”) on August 12. This staff provided the nucleus for the X Corps staff.
The X Corps plan called for the 1st MarDiv to conduct an amphibious assault to seize Inch’on on September 15 (D-Day), secure a beachhead, advance as rapidly as possible to seize Kimpo Airfield to provide a base for close air support aircraft, and clear the south bank of the Han River. It would then assault across the Han, seize Seoul, and secure the high ground to the north. It would fortify a line to the north with reduced forces and await relief (tentatively by 3d InfDiv still in the States). The division would then recross the Han and seize a line 25 miles southeast of Seoul. The 1st MAW would provide close air support, air warning, and air control operating from Kimpo Airfield. The Pusan breakout would commence on September 16. It was considered that the NK might reinforce Inch’on–Seoul with units attacking the Perimeter. The closest were the 3d, 10th, and 13th divisions astride the Taegue-Taejon–Seoul Highway, the route the main breakout force would take.
The 7th InfDiv would land behind the marines on about D+4 and advance to secure high ground south of Seoul and the Han. It would move into Seoul, secure a line to the north to the right of the 1st MarDiv, and then conduct a reconnaissance-in-force south of Seoul where it would secure a line. Alongside the 1st MarDiv to the east, the two divisions would face south to provide the anvil to meet NK forces withdrawing before the hammer of the Eighth Army breakout.
The tides were a major planning factor. The navy wanted to make the perilous approach up the Flying Fish Channel during daylight. This meant the four-hour approach would arrive at 1130hrs and low tide. The tide would be receded by 1300hrs. The next high tide allowing landing craft to run ashore was at 1919hrs. Wolmi-do would have to be secured in the evening with only two hours of light remaining for the marines to clear the island which was honeycombed with fortifications. After the evening tide receded they would have to spend the night on an incompletely secured island at risk of infantry attacks across the exposed mud flats. The main landings into Inch’on would then be conducted during the morning high tide. This would allow the NK much of the previous day and all night to bring in reinforcements and position troops to meet the main landings.
The approach would have to be made in the pre-dawn dark and the first landing to seize Wolmi-do made during the morning high tide. The main landings into Inch’on would occur in the evening with just enough time to secure beachheads. While doctrine called for assault troops to land in amtracs, because of the 15ft seawalls, those aimed at Beach Green and Beach Red would have to land from Landing Crafts, Personnel and Vehicles (LCVPs) using scaling ladders. Amtracs would be used on Beach Blue as there was no seawall.
After a pre-landing bombardment the marine plan called for 3d Battalion, 5th Marines (3/5) to assault Wolmi-do (specifically, the 50yd-wide Beach Green on the small North Point peninsula) at 0630hrs (L-Hour), September 15. This would secure the islands dominating the harbor and the tide would soon ebb. The marines on Wolmi-do and Sowolmi-do would be on their own waiting for the evening high tide. Naval and air bombardment would continue on Inch’on and approaching NK reinforcements be forced to move in daylight.
Just prior to the landing MajGen Almond proposed three inane plans that were fortunately rejected. One was for the 8227th Army Unit (Eighth Army Raider Company), reinforced by 100 handpicked marines, to paddle 3 miles to shore in rubber boats to land 8 miles north of Inch’on, move 9 miles overland by foot to Kimpo Airfield, seize it in a surprise attack, and hold until relieved. Smith wisely refused to provide the marines, pointing out that the 5th Marines had only just withdrawn from combat and was under-strength. Furthermore, 500 17-year-olds had been pulled out of the division, there was no time for the unit and the re-assigned marines to rehearse together, and lastly, Smith needed to retain his experienced troops. It is highly unlikely the 224-man unit could have held out until relieved by the landing troops, which took three days to reach the airfield. Almond still planned to launch the raiders without the marines, but it was cancelled at the last minute. It was earlier planned to land this unit, without marines, at Kunsan far to the south to create a diversion and make it appear a division was landing, a tall order for a 124-man unit. Elements of three NK divisions in the area would have made short work of it. Another plan proposed by Almond was to land a battalion of the 32d Infantry, 7th InfDiv on Wolmi-do in the evening during the main landings, load it aboard marine trucks and tanks, and drive 20 miles to seize high ground on the edge of Seoul. Smith rejected this idea too, stating he could not afford the vehicles and felt it was a tactical impossibility. This force would also have had to be supported by air and naval gunfire; artillery on Wolmi-do was out of range. Besides tactical impracticality, all resupply would have to be by air. It took the marines eight days to reach the battalion’s proposed objective. Both schemes also would have placed restrictions on fire zones forward of the advancing marines, an unnecessary hindrance.
Looking south, Inch’on burns after heavy naval and air bombardment. The white rectangular area on the waterfront beneath the black column of smoke is Beach Red where RCT-5 landed. Just to its left and hidden mostly by the smoke is Cemetery Hill. The dark area near the upper center with white smoke to its right is Observatory Hill. (USN)
The navy would control the airspace around Inch’on, with the Far East Air Force restricted from conducting operations within a 100-mile radius of Inch’on unless requested by JTF7. The air force had opposed placing such a large area under naval control, but it was approved. The navy and marines would conduct continuous air patrols in a 25-mile radius around Inch’on.
The main landings would occur at 1730hrs (H-Hour). North of Wolmi-do, the 500yd-wide Beach Red was situated on the Inch’on waterfront, but outside of the main harbor. The 5th Marines, minus 3/5, would land here and push inland up to 1,000yds to establish a 3,000-yd line, the O-A Line, stretching from a few hundred yards north of the beach and south to the east end of the Inner Tidal Basin encompassing Cemetery and Observatory hills. 1/5 would land on the left and 2/5 on the right, with both battalions coming ashore in a column of companies.
Some 4,000 yards to the southeast of Beach Red lay the 1,000-yd wide Beach Blue on the edge of Inch’on. Doctrine called for a division’s two assault regiments to land adjacent to one another unless terrain restrictions or enemy dispositions dictated otherwise. In World War II the marines conducted only two landings where the landing force was separated by a considerable distance, at Tinian and Guam. The men of 2/1 would land to the left on Blue 1, and 3/1 on Blue 2 to the right; each battalion would land with two companies abreast aboard amtracs and preceded by army amphibian tanks. Blue 3 was south of and at a right angle to Blue 2 and was a questionable alternative. They would fight through an industrial area up to 3,000 yards inland to secure the 4-mile O-1 Line. The 1st Marines would control by fire the Inch’on–Seoul Highway. Key objectives were Hill 117 northeast of the beach; Hill 233, a long ridge 1,500 yards southeast of the beach; and Hill 94, a small cape flanking the beach. The plan called for 1/1 to come ashore in LCVPs 45 minutes after the assault battalions. There were no plans for RCT-5 and RCT-1 to link up on D-Day.
When Beach Red was secured, eight LSTs would beach to off-load critical ammunition and supplies before nightfall. Two artillery battalions and support troops would land on Wolmi-do at 1900hrs to provide artillery support to the marines on the mainland. The marines would maintain defensive positions through the night and commence clearing the remainder of the city, link up, and continue toward Seoul.
Little was known of the North Korean order of battle, dispositions, strength, and capabilities deep in the rear areas. Many units were stripped of troops to send south to Pusan. There were still substantial units in the area, although they were dispersed and under-strength.
In addition, Japanese maps and hydrographic charts were often inaccurate and outdated. Villages, streams, roads – even entire hill masses – were incorrectly positioned or omitted. Different grid systems were used, making location reporting and fire control difficult.
Detailed hydrographic data on the port of Inch’on was scarce and what was available was often suspect or conflicting. Aerial photography augmented maps, but differences in altitude and perspective complicated their use. The height of the seawalls could not be accurately determined from aerial photos. It was determined there were no manmade boat obstacles.
In an effort to collect up-to-date intelligence on the Flying Fish Channel, Wolmi-do, and Inch’on Harbor, the navy sent Lt Eugene F. Clark with two Korean interpreters by boat to Yong-hong-do island 15 miles southwest of Inch’on and on the west side of the Flying Fish Channel. Accompanied by rations, rice, and weapons, Clark established a small private “army” of teenagers from the island’s friendly inhabitants and set up camp on September 1. Some of the teenagers served as coast-watchers to secure his base, the NK occupied Taebu-do 3 miles across East Channel. Others posed as fishermen to reconnoiter Wolmi-do and the harbor, reporting back to Clark with descriptions and locations of defenses, seawall and pier data, current speeds, and water depths. He captured NK sampans to obtain information from prisoners and reconnoitered the harbor himself. He even walked the low-tide mud flats proving that in some areas they were sufficiently firm for foot and even vehicle traffic. He also discovered that the lighthouse on Palmi-do was still operational. When Clark radioed this information he was directed to turn on the light at midnight, September 14.
Two LSTs rest on the mud flats after the morning tide receded. Some areas of the flats could support vehicle traffic; it was originally thought that a grounded LST would break its back, but this fear proved unfounded. (USN)
Marines examine an abandoned NK trench on the outskirts of Inch’on. In the background is one of the city’s industrial areas. Virtually every piece of defendable terrain inside and outside Inch’on was honeycombed with fortifications. Fortunately the NK did not possess the troops in the area to man them. (USMC)
A Soviet-supplied NK 76.2mm M1942 field gun emplaced on Wolmi-do. The wheels were intentionally removed. This extremely effective weapon served as NK divisional artillery, and was also employed as an anti-tank and coastal defense gun. Note the rice straw sandbags. (USN)
A less successful reconnaissance was conducted on the night of 11–12 September by Eighth Army Raider Company. They and a smaller group of British sailors reconnoitered two beaches at Kunsan south of Inch’on. The unit was detected and taken under fire with the loss of two dead and one wounded. The reconnaissance was an effort to determine if Kunsan’s beaches were suitable as alternative landing points.
In early September X Corps estimated that there were 1,500–2,500 NK troops in the Inch’on area, mostly recruits. Many of these may have been press-ganged South Koreans, a common practice. Prior to the landing the enemy estimate was revised to c.7,000 in the Inch’on–Seoul area: 1,000 in Inch’on, 5,000 in Seoul, and 500 at Kimpo. The numbers and capabilities of units that could reinforce the area after the landing were unknown, but were thought to be within a few days’ march. It was assumed that some tanks would be in the area, but numbers and locations were unknown. NK air force capabilities were limited, and they possessed no jet fighters or bombers. Several models of Soviet-supplied Yakovlev and Lavochkin prop-driven fighters were in use.
The formal details of the NK defense plan are unknown, so historians can only assess their actual movements and actions. It is unlikely that they possessed a well developed plan. Units available in the Inch’on–Seoul area were in constant turmoil as they passed through to the south. Other units were constantly being ordered to send replacement drafts south. There was also no single known major command in control of the area other than possibly some regional administrative headquarters. Such a headquarters would not have been suited for the planning, command, and control of defensive and counterattack operations. Part of the plan may have been to use whatever units were available, to include rear service troops, as ad hoc defense forces. Elements of the 18th and 19th KPA Divisions were known to be in Seoul. The NK probably felt there was little chance of a major amphibious landing directly into Inch’on because of the very reasons that made the JCS, navy, and others hesitant.
Little was known of NK defensive techniques as UN forces had only experienced their offensive tactics. Naval forces were experienced with NK coast artillery: 76mm, 85mm, and 122mm. These Soviet-made guns (mostly 76mm at Inch’on) were often emplaced in open positions. There were scores of prepared artillery, mortar positions, and trenches throughout Inch’on, but most were unoccupied. Over a hundred hardened positions were detected by aerial reconnaissance. It was assessed that the NK had only minimal troops in the area to defend against amphibious raiders. Because of the many prepared, but unoccupied fortifications, the NK probably planned to rush troops to the city from Seoul if a major landing looked imminent. This was another good reason for US forces to establish beachheads within Inch’on on D-Day itself. Delaying the establishment of beachheads would have given the enemy the cover of darkness to move up reinforcements. There were no air defenses.
The marines established their beachheads and cleared Inch’on reasonably easily. Resistance was uneven in the intervening towns on the road to Seoul, Ascom City, Sosa, Kimpo, and Yongdungp’o. Counterattacks were piecemeal, usually small in strength and unsupported by artillery. While the original NK plan may have envisioned a defense on the Han River, resistance there was light. The NK establlished their defense line in the hills on the west and northwest sides of Seoul. Strongpoints were built within the city, and streets were barricaded, but there were no identifiable defense lines within Seoul.