Inchon—The Analysis Of A Gamble

The passage of more than three years’ time finds the amphibious assault at Inchon, Korea, remembered even by professionals as “brilliant,” “daring,” and “skillful.” Such press copy adjectives are not inaccurate, for certainly the landing at Inchon by the United States Marines supported by the U. S. Navy in September, 1950, was daringly conceived, skillfully executed, and brilliantly successful. A critical analysis of that campaign, however, a study of the obstacles which were faced and the hazards which were accepted, will reveal how great were the chances of disaster. Certainly any objective review of Inchon will hoist warning signals which instruct that the success of this operation should not be accepted, per se, as a yardstick of future capability.

The obstacles to an amphibious assault at Inchon in September of 1950 were very numerous, and can be divided into three categories: the physical obstacles, the military handicaps, and the political hurdles.

The physical obstacles which favored an amphibious assault at Inchon are encompassed in two words: tide and terrain. Korea’s western shoreline boasts herculean tides which average 29 feet, and at their peaks touch 36 feet. The numerous islands which bracket Inchon to seaward form a natural pocket into which the Yellow Sea makes periodic surges. One dividend of this sluggish and heavy tide is the mud banks which time 3 has accumulated there.

“Flying Fish” channel, as a consequence, is a twisting, deadend sealane which winds northeasterly into Seoul’s port of Inchon. It is neither wide nor deep. These features, aggravated by the aforementioned tide and mudbanks, make navigation treacherous in daylight, even without the additional hazards of nighttime, enemy gunfire, and minefields.

Standing beside Inchon, and connected with it by a man-made, half-mile long cause way, is the island of Wolmi-Do. This pyramidal hump of land rises 351 feet above the sea, commanding the immediate area, including “Flying Fish” channel. Its location, therefore, makes it a natural strong point. Besides, at the time of the Inchon landing, Wolmi-Do was heavily fortified with a variety of coastal artillery and resembled a miniature Iwo Jima.

Any amphibious penetration of Inchon, therefore, had first of all to either neutralize or capture Wolmi-Do, else it would stand in a flanking and rearward position to foil any attempt to seize and exploit the port area. The narrow, winding, and shallow channel with its five knot current would accommodate only destroyers. In any gunnery duel with Wolmi, attacking vessels would be unable to maneuver and would even find turning about difficult (DesRon 9 which bombarded Wolmi actually anchored during the first day’s bombardment to counteract the current.)

The city of Inchon was itself protected from the tides by a twelve foot stone seawall. Pier space and handling equipment were minimal, even counting the tidal basin piers. Inchon was a mediocre logistics port even after it was won; but it was still the best and biggest on the West Coast.

The geography of the immediate area near Inchon necessitated that any amphibious assault be made into the heart of the city, across the mudflats and up the seawall. Ingress and egress for troops and supplies would have to be blasted in the seawall. The fact that every house and building in the port area would give shelter and cover to the defenders was yet another obstacle. Inchon would represent the Marine Corps’ first attempt to make an amphibious assault into the heart of a city.

The timing of the tides on September 15, 1950, presented another hazard. The first high tide for that date occurred at 0630. The planners would use this one to overwhelm Wolmi- Do. The afternoon high tide commenced flooding about 1730 with sunset following at 1843. In other words, in less than two hours of daylight the Marines had to land, spread out, and seize enough space to maintain a toehold during the first night. Moreover, in this same short time, sufficient supplies had to be brought ashore to last until the next morning’s tide would allow replenishment. In effect, this tidal predicament meant that LSTs would have to make an assault landing concomitant with the troops, beach themselves and lie high, dry, and exposed to the enemy until the next day.

Yet another hazard was mines. Inchon was acknowledged to be a most excellent spot for them; in fact mine experts felt it could well be made impregnable. If “Flying Fish” channel could be sown with a variety of types, the muddy water would obscure them and any vessel which struck one would almost surely block the channel. At this stage of the Korean War, the U. S. Navy’s capacity for combatting mines was at best imperfect.

These, then, were the physical handicaps sufficient to make any amphibious planner pause. The military obstacles were equally awesome.

At the time proposed for Inchon, the UN troops had been driven behind the Natong River into a crescent shaped perimeter roughly 30 miles from Pusan. Pressing around it with frantic zeal were thirteen Red divisions—some 143,000 troops. Our forces at this time numbered about 120,000. Their pressure shifted continually. One day it would be exerted upon the northern flank; then the effort would shift to the southern flank; then to the center. Nowhere was the UN reserve strength sufficient to guarantee against breakthrough, encirclement, entrapment, and disaster. The line was being held only by a stubborn, fire-brigade type defense, shifting the few available troops to meet each threat as it developed. The First Provisional Marine Brigade had been doing this linebacking task since their arrival on August 2.

Any amphibious landing, therefore, would require that part of these perimeter-defending troops be taken out of the line, forcing disobedience to a cardinal ground rule: never divide your forces in the face of a superior enemy. The chance that the Reds would capture Pusan as we invaded Inchon would have to be accepted.¹

Another, and more serious military hurdle, was the lack of time—insufficient time for planning and organization; insufficient time for the assembly of intelligence; insufficient time for minesweeping; and no time for rehearsal. Troops, supplies, and ships must rush helter-skelter to the scene, even if some of the latter could not be combat loaded. The 1st Marine Division, hastily assembled and augmented by recalled reserve units, steamed westward to join and absorb the 1st Provisional Marine Brigade. Landing vessels were requisitioned and recommissioned back into the U. S. Navy overnight; skippers for them were hurriedly located, some of them, regretfully, with no LST experience.

The unlikelihood that surprise could be achieved at Inchon because of the necessity to reduce Wolmi-Do has already been mentioned. The rigid schedule imposed by the tides has also been noted. There was yet another factor which added to the insecurity. Any invasion of Korea would stage from Japan, admittedly an insecure base. In all other assaults across the central Pacific during World War II, the U.S. Navy had had the advantage of departing from a secure base and staging area. With the frenetic preparation necessary for Inchon and the large numbers of enemy agents believed to be afoot in Japan, there was little chance that such an immense undertaking could be concealed. Only the intended point of landing, it was hoped, would be secure.

Perhaps the most burning problem raised by an Inchon assault was the basic problem: would a landing there (approximately 150 miles behind the main lines) reduce the enemy’s grip upon the perimeter? Was it too far behind the front? There was strong and responsible backing for the contention that the landing should go in near Kunsan, further south, where there were fewer physical hazards. True, a successful invasion of Inchon would make inevitable the capture of Korea’s capital, Seoul, an immense psychological prize. To General MacArthur, this possibility seemed of the highest importance.

In addition to the physical and military hurdles at Inchon, there was one final political facet which had to be given attention. What effect would a landing at Inchon have upon the Chinese, already poised and rattling their sabres along the Yalu? Vague and disturbing reports were drifting in that the Chinese would intervene if UN forces took any step which threatened their security. Would a Kunsan landing be any less objectionable to them? Many thought it would be.

If Inchon had several disadvantages, it also had many advantages. First of all, Inchon was the best port on the west coast. The Inchon-Seoul area was the hub-area of the wheel from which the country’s railroads and highways radiated. Capture of Inchon would effectively extinguish most of the Red Army’s logistics. Capture of Seoul, as General MacArthur predicted, would be a psychological prize, the immensity of which would be incalculable in the Far East. A successful landing at Inchon would shorten and probably end the North Korean aggression. The Supreme Commander believed that the Reds considered an Inchon landing impossible, and would be taken by surprise. He even recalled the classic lesson—-General Wolfe’s backdoor assault on Quebec’s Plains of Abraham— where daring and surprise had won the day. But despite these advantages, most of the Navy and Marine officers who examined the balance sheet felt the prospects of failure outnumbered the prospects of success.

In the face of so many risks, and so many objectors, how did Inchon come to be selected? First of all, by a simple process of tactical elimination. The west coast of South Korea promised more in tactical results from an amphibious landing than did the east coast.

The eastern shore offered a few excellent landing areas. At the same time it was generally mountainous, with but few flat areas and fewer towns, roads, and rail lines. The west coast, on the other hand, embracing almost no satisfactory landing areas, was the inhabited and alluvial side. Any west coast landing would be closer to the fighting front in both time and strategy, if not in distance. From these facts, the west coast was naturally favored.

Once the west coast had been selected, there were three general areas at which an amphibious landing could be made: Kunsan and Inchon in South Korea and Pyongyang in North Korea. The latter was obviously too deep in enemy territory and too close to Manchuria. Inchon had the best port, and was only eighteen miles from Seoul. The area near Kunsan was the better of the three in the physical sense. But General MacArthur rejected that location: “The amphibious landing is the most powerful tool we have,” he told the naval planners. “To employ it properly we must strike hard and deeply in enemy territory.”²

Inchon’s selection was partly an extension of an earlier decision to introduce our troops into South Korea via that port. When President Truman first authorized the use of American ground forces late in June, the battle lines were still north of Inchon, although collapsing rapidly. Orders were issued to plan an administrative landing at Inchon; for a few days this went ahead until it became obvious that American troops would have to land much further south than Inchon. Thus developed the unopposed east-coast landing at Pohang on July 19th, a little publicized landing which the writer feels had a great part in the final results.

But Inchon, having once been proposed, continued to radiate a magnetic charm—and the idea stuck. In fact, all research, planning, briefing, and intelligence effort which subsequently followed seemed to many merely justification of the original selection rather than selection by logic. For once, a syllogism seemed to work in reverse.

The pros and cons of Inchon can be summarized like this—physically Inchon would be extremely difficult but not impossible; militarily, it might trap, defeat, and destroy the NK Army—but so would landings at other locations. Politically—well, no one could be sure what the political effects would be. Security-wise, Inchon was certainly violable and doubtful. Thus with the clarity of hindsight, Inchon could only be assessed as a high-odds gamble—MacArthur’s gamble that opposition there would be light.

No one can dispute the results of Inchon which amply vindicated and justified the decision to land there. However, the success and achievement at Inchon must not give future planners the false and fatal impression that any and every beachhead can be won, no matter what the physical handicaps. Or, in different words, the danger of Inchon is that the basic premise of amphibious assault— “any beach can be seized by properly trained landing forces provided first that it can be isolated by air power and neutralized by sea- power; and second that surprise can be achieved”—might be altered.

Any analysis of Inchon must also be an analysis of General MacArthur’s amphibious doctrine. It was he who selected and insisted upon Inchon; it was he who unhestitatingly accepted the risks. His also must be the credit for the achievement.

Inchon was General MacArlhur’s first major amphibious assault as well as his first command over Marine troops and his first control of large carriers. In his Southwestern Pacific campaigns he had engineered many amphibious landings. Always before he had attacked large land masses or chains of islands where a strongly contested beachhead was avoided. His strategy in those campaigns had been “to hit ’em where they ain’t.”³ In this he had succeeded. His insistence upon Inchon and the nub of his gamble was a reaffirmation of that strategy; the Reds would consider an Inchon assault insane and impossible; it would take them by surprise and opposition would be light.

As the time for Inchon neared, several attempts were made to dissuade the General. The planners were determined to enumerate every danger and to pinpoint every risk. He heard all arguments in quiet silence, and then confirmed Inchon as the landing point. “The Navy has never let me down in the past,” said he, “and I am positive it will not let me down this time.”⁴

Only once did his rock-like confidence soften. On D+3 day, with the Marines having captured Wolmi and Inchon and now plunging towards Seoul, there was yet no evidence that pressure around the Pusan perimeter was relaxing. So far General Walker’s VIII Army had been unable to escape. Aboard U.S.S. Mount McKinley, General MacArthur sent for his senior assistants and announced that Inchon had not achieved the desired results; they must make immediate plans to strike again, closer to the front lines, perhaps at Kunsan. But before the day passed, the news came that Walker had cracked the perimeter and was hammering northward. The North Korean Army suddenly dissolved like a wet cube of sugar.

To the naval student, what education does Inchon give and in what respects did it resemble other historic invasions? In certain respects, Inchon was similar to World War I’s Gallipoli—both were hastily assembled, only Inchon more so. Gallipoli, however, had nothing behind it; behind Inchon lay a generation of amphibious theory and practice. Most of World War II’s landings had required months of planning and preparation —Normandy had taken a full year—but Inchon was planned and executed in the crash time of only 23 days.

Inchon resembled Guadalcanal in many ways. The old hands of the First Marine Division who made both assaults must have recognized the same pattern—the confusion, the rush, the lack of planning. Both of them had been shoe-string affairs. Even in the broader tactical aspects, Inchon and Guadalcanal were much alike. On both assaults, a major purpose had been to seize an airfield— Henderson at Guadal, Kimpo at Seoul. On both, a major port and base were at stake—Tulagi at Guadal, Inchon itself. And even more striking was the comparison that at both Guadalcanal and Inchon, the potentialities for disaster were enormous.

The Inchon landing also had similarities to Tarawa. As at Inchon, Tarawa’s tides had played a major role. Like Inchon, Tarawa could have been postponed a month with better results. However, at both Tarawa and Inchon, the need for strategic speed exceeded the requirement for tactical safety. Thus the story of Inchon landing is the story of the Pacific War repeated. It used no new tactics, developed no new doctrine, introduced no new weapons. Inchon added little to the U. S. Marines’ art of amphibious assault. It did reaffirm the emphatic proof of the Pacific War—that a difficult beach could be seized.

The lessons of Inchon are many. First of all, no future amphibious assault should be jeopardized by inadequate preparation. At Inchon only the fulfilment of the primary precept of amphibious war—surprise—the soundness of the techniques employed, the ineptness of the defense, and the failure of their intelligence averted a potential disaster.

The necessity for speed must never outweigh careful preparation. Secondly, the choice of both site and timing should, if possible, be the prerogative of the U. S. Navy and the U. S. Marine Corps. At least, certainly, these should have a veto power in decisions concerning these critical elements. For there is no doubt that the medal of failure would be pinned upon the Navy’s breast even more quickly than the badge of success. Thirdly, a major lesson of Inchon is to reaffirm the value of the amphibious assault weapon. While Inchon’s basic pattern was unchanged and while there were no new techniques or doctrines developed, the assault confirmed the soundness of our present doctrines and demonstrated afresh the power of decision which the amphibious assault possesses.

The final lesson comes from Inchon’s champion, General MacArthur himself. “I realize,” he told the planners, “That Inchon is a 5000 to 1 gamble. I am used to taking those odds.”⁵

5000 to 1 is certainly the outer odds limit for an amphibious assault.