Inchon, and Operational Maneuver From The Sea

The surprise North Korean invasion of South Korea steamrolled over lightly armed and poorly trained South Korean troops. Even the addition of US airpower and troop units did little to slow the onslaught. The defenders were soon pushed back to a small perimeter defending the port of Pusan. Pusan port was both their logistical lifeline, and presented the escape route should the perimeter fail.

But all was not lost. By the end of the summer of 1950, significant US troop units were available for commitment. Further, the North Korean army had stretched its lines of communication about as far as they could go.

Conventional military thinking called for the deployment of fresh forces into the Pusan perimeter, where eventually they could stage a counterattack, break out of the siege, and force the North Koreans back.

But a glance at the map would show that Korea is a peninsula. With the long shorelines on both coasts, North Korea had been forced to concentrate its ground forces at the Pusan perimeter, and its lines of communication were lightly defended.  These flanks were ripe for attack. And the commander of UN forces in Korea, General of the Army Douglas McArthur, was a past master of amphibious assaults, having used them brilliantly in World War II.  To our eyes some 60 year later, the choice to stage an amphibious assault seems easy.

Except…

The large scale demobilization of the services after World War II included a deliberate choice to mothball virtually all of the Navy’s amphibious warfare capability. The advent of nuclear weapons had convinced Navy planners (and Army planners as well) that any large scale amphibious landing would present a concentrated target tempting an enemy to use atomic weapons against it. A single atomic weapon would not only doom any landing, it would impose catastrophic losses of both shipping and manpower. And so the ability to land an expeditionary force against a defended coast had largely been foregone.

Further, while a brief glance at the map shows Korea as a peninsula, a detailed examination shows it to have some of the most inhospitable coasts, almost completely unsuitable for landings with the technology of the time.  Further, with the slashing of the US amphibious fleet, logistics over any assault beaches would be impossible. It’s one thing to land a force, it’s a far more difficult task to keep it supplied.

General MacArthur, after careful study, chose to conduct an amphibious assault, and chose the port of Inchon (which serves the South Korean capitol of Seoul) as the objective.  Located about halfway up the peninsula on the west coast, Inchon was lightly defended, and was a sufficiently deep envelopment that the North Korean army could not easily shift forces from Pusan to Inchon. But Inchon lies at the end of a long, notoriously treacherous channel with some of the worlds most complex tides. Further, rather than assaulting across open beaches, the troops would have to attack across a seawall onto open paved areas with little or no cover and concealment.

The Joint Chiefs of Staff had grave misgivings about the risks involved. Finding, mobilizing, training and deploying sufficient amphibious shipping and landing craft would be an enormous challenge, and the risks involved. If the Inchon channel was mined, or should the landing force otherwise falter, the invading force might be destroyed in detail.  The failure of any landing attempt would almost certainly cause support for our actions in Korea to collapse.

But the prospect of cutting off the North Koreans and destroying their invading army was tantalizing, and despite their doubts, the Joint Chiefs allowed the commander on the scene to follow his own course.

And so, on this day, September 15, in 1950, elements of the 1st Marine Division, with troops of the 7th Infantry Division in follow on waves, were landed by the US Navy at Inchon, in what is widely hailed as a strategic masterstroke, and one of the most decisive victories ever.

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The landings came as a strategic and tactical surprise to the North Koreans. With their lines of communication threatened, coupled with a breakout by UN forces in the Pusan perimeter, the North Korean army was soon fleeing South Korea in disarray. Had the landing forces at Inchon moved faster to retake Seoul, the North Koreans might have been trapped and destroyed. As it was, they barely managed to retreat not only from South Korea, but northward through their own country to the line of the Yalu River, where soon “volunteers” from the People’s Liberation Army of China would come to their rescue, and dashing hopes for any rapid victory and a lasting peace.

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First Lieutenant Baldomero Lopez, USMC, leads the 3rd Platoon, Company A, 1st Battalion, 5th Marines over the seawall on the northern side of Red Beach, as the second assault wave lands, 15 September 1950, during the Inchon invasion. Wooden scaling ladders are in use to facilitate disembarkation from the LCVP that brought these men to the shore. Lt. Lopez was killed in action within a few minutes, while assaulting a North Korean bunker. Note M-1 Carbine carried by Lt. Lopez, M-1 Rifles of other Marines and details of the Marines’ field gear. Photo number NH 96876. Image Courtesy of the Naval Historical Center.

Mastery of the seas and the ability to land forces upon hostile shores gives a ground commander a freedom of maneuver that allows him to choose the time and place of his assault, and usually provides him the opportunity to attack an undefended or lightly held position. The use of such maneuver to unhinge an enemy is a key to the operational art, whether it be the “Hail Mary” sweep to the west during Operation Desert Storm or the amphibious envelopment at Inchon in 1950.  Since that time, the US has been careful to maintain both the shipping and the expertise to allow it to conduct amphibious assaults worldwide.