Landing at Inchon: Foolish Risk or Calculated Gamble?

Campaign Analysis: Operation CHROMITE

The Ultimate Challenge for the Commander is deciding on where and when to commit forces to best leverage available combat power against the opponent.
General Douglas MacArthur has been criticized for his decision, even though it succeeded, to make the invasion of Korea at the harbor of Inchon. This paper explores the legitimacy of that decision based on the principles of military power.

 

A popular military aphorism is that victory has a thousand fathers, while defeat is an orphan. The American invasion of Inchon during the Korean War must certainly be the exception to this. General Douglas MacArthur, loved by some, hated by others, rightfully deserves all of the credit for such a bold and audacious decision. In retrospect, his decision deserves perhaps a bit more circumspection. If Inchon had failed, whether tactically or strategically, not only could the war’s outcome have been different, but most certainly MacArthur would have been lambasted in his own time, as well as our own by arm chair theorists and generals. Was his decision soundly based in military principles, balanced by ends to means? Or was it a gambler’s last toss of the dice?

America’s war aims at the onset of the Korean War were simple: Drive the North Korean People’s Army (NKPA) out of South Korea, back across the 38 th parallel and re-establish peace on American terms. These were the explicit aims. The strategic priorities will sound strikingly familiar to those familiar with strategic debate in this era of Bosnia, Somalia, Haiti and Operation Desert Storm: End the war as quickly as possible and keep U.S. casualties to a minimum. Even in the 1950s, there was a political drive to keep wars short and bloodless; to attain national ends without expending resources. Perhaps the national tendency to hope to attain something for nothing is a fundamental characteristic of America.

For the North Koreans, the opposite was true. Kim Il Sung’s aim was to reunify the two Koreas. Since he could not accomplish this politically, he resorted to military means to gain a political end. He had committed North Korea’s limited resources and manpower utterly and completely to the reunification of the Korean peninsula. Kim Il Sung may not have realized it, but he had two possible branches of strategic priorities. The first was to drive the Americans out of the Pusan Perimeter and back to Japan, thus allowing him time to consolidate his hold politically, socially and militarily on Korea. The second branch, far more subtle, would have been to keep the Americans bottled up at Pusan and continue to attrit American lives, while consolidating his hold and strengthening his long logistical tail. By killing Americans, North Korea could make victory appear extremely costly to the American government and perhaps wear down the political will to fight. The political will to fight would be backed up by how the American military would actually conduct the fight.

American doctrine has historically been framed by the notion of preparing to fight the next war as the last one was fought. While this type of doctrinal thinking came back to haunt the U.S. in Vietnam; strangely enough, it was the correct approach for Korea. The American military had of course, only just finished fighting World War Two five years prior to North Korea’s invasion of South Korea. While the U.S. force structure had been dramatically drawn down and was unprepared to fight the next war, its doctrinal approach to waging war had not changed. American doctrine during the previous war was offensively oriented, relying primarily on the infantry to hold key terrain once the enemy had been pushed off. The attrition of enemy forces was secondary to seizing and defending ground. Offensive action was used to envelop a foe’s flank, without resorting to frontal assaults. Armor’s role was to gain the initiative either with an envelopment or a penetration at a weak point in the enemy’s front. Tanks were regarded as the best weapon to kill another tank. The doctrinal use of artillery and close air support made great strides during World War Two. By the end of that war, the U.S. Army was very good at conducting offensive war, largely because they did not have to defend their own homeland as the German Army had been forced to do. However, American defensive doctrine was weaker. Reliance on fortified strongpoints made penetration of American lines easy, as the 1 st Armored Division discovered to its regret during the opening phase of the Kasserine Pass battles. A strongpoint defense with mobile armored counterattack forces might work against an attacking tank division, but it was ill-equipped to deal with an infiltrating infantry force which attacked at night, bypassing the strongpoint and raided logistical bases. On the whole, the experience of the previous World Wars had molded the American commanders’ methods of waging combat.

General Douglas MacArthur had been a regimental commander during World War One and an Army commander during World War Two. During both of his previous experiences, he had relied on boldness, audacity and the offensive to gain and maintain the initiative over his opponents. MacArthur’s brilliant use of amphibious operations in the Pacific against the Japanese had already provided him with the experience necessary to decide on an amphibious landing at Inchon, far behind enemy lines, to cut off the North Korean logistical lines of communication and quickly recapture the capital of South Korea, Seoul. As the American doctrinal approach to the operation was the same as in the previous conflict, so essentially were the forces at MacArthur’s disposal

The U.S. Army force structure was centered on the pre-eminence of the infantry divisions, with integrated armor support. An infantry division had three regiments, with three battalions each, and four infantry companies per battalion. The division also had one tank battalion, parceling one company of M-24s (outgunned in comparison to the Russian made T-34 which the North Koreans used) to each regiment. During the drawdown which followed World War Two, the number of infantry battalions per regiment was reduced by one. The infantrymen’s arsenal largely consisted of small arms, mortars and heavy machine guns. However, the infantry had no truly effective anti-tank weapon. The standard issue 2.36 inch rocket was no match for the thick armor of the T-34. The three division artillery battalions (one per infantry regiment) had also suffered cutbacks, dropping from three batteries each to two.

With this structure, the X Corps, commanded by Major General Almond, was established to conduct the amphibious assault at Inchon. X Corps consisted of the 1st Marine Division, plus one regiment withdrawn from the Pusan Perimeter in order to bring that Division to a full wartime strength of three regiments, and the 7th Infantry Division. While X Corps was the assault force, overall command and joint support was under the umbrella control of Joint Task Force (JTF) 7, with seven subordinate task forces. JTF-7 was a true joint operational command, incorporating Navy, Army and Marine units in order to support the assault force. JTF-7 would strike the North Koreans at a weak, unprepared point, effecting surprise and mass before the North Koreans could react.

North Korean military doctrine closely resembled the Chinese model. Mao Tse Tung’s approach was to avoid strong points and infiltrate an enemy’s lines to hit the weakly defended rear areas, in order to destroy vital logistical areas. The North Koreans were not as road bound as the American army was, which gave them more flexibility than the Americans. North Korean equipment was largely Russian and Chinese made, including the awesome Russian T-34.

The North Korean force structure closely resembled the Chinese and Soviet triangular formation. On the offense, the two up and one back method was used. On the defense, this formation was reversed. The infantry division’s main body was usually preceded by four tank battalions, whose objective was to punch through an opponents main defenses and continue on into the rear areas, leaving the infantry to mop up. While sorely lacking in air support with only nineteen outdated Soviet aircraft and almost no navy to speak of, the North Koreans did possess the T-34 tank and towed artillery.

In the Inchon/Seoul area, the 3 d, 10 th and 13 th Divisions were astride the Seoul-Taejon-Taegu highway, within easy striking range of the landing areas. Some 400 soldiers of the 3 d Bn, 226 th Independent Marine Regiment and elements of the 918 th Artillery Regiment defended Wolmi-do Island, the invasion’s initial objective. North Korean shore artillery consisted of 75mm guns inside concrete revetments.

Operation CHROMITE succeeded for several reasons. First, the U.S. (with British assistance) was able to establish and maintain air supremacy; strike aircraft were able to hit North Korean units during daylight hours and attrit units in the Seoul-Inchon area. Control of the skies permitted the isolation of the invasion area and prevented reinforcing units from reaching the invasion area. Control of the sea permitted the logistical support of the assault force without fear of interruption by enemy surface or submarine forces. The presence of a secure logistical base on Japan ensured a smooth flow of supplies, both to units at Inchon as well as Pusan. With naval gunfire support, the Americans also pounded defensive positions on Wolmi-do Island with high explosives and napalm, effectively neutralizing the North Koreans. Securing the island was absolutely critical to success of the operation, because without it, the North Koreans could enfilade the invading amphibious forces with artillery and small arms fire. The capture of key terrain at Inchon, specifically Cemetery and Observatory Hills was also crucial in ensuring that X Corps would have a secure beachhead. Seizing the high ground east of Inchon at Yongdungp’o and Sosa gave the American the advantage of holding key terrain from which to continue their operations to the east. The capture of Kimpo airfield on the morning of 18 September facilitated the staging of Marine Corsairs flying Close Air Support missions for the Marines on the ground. Further, small unit actions, such as the capture of the causeway linking Wolmi-do with Inchon illustrate the value of highly trained, motivated, veteran soldiers as a combat multiplier.

In retrospect, the preconditions for victory were already and in place and the outcome of foregone conclusion; the combination of U.S. naval and air supremacy seem to have guaranteed it. However, the most critical action was Douglas MacArthur’s single minded determination to land X Corps at Inchon instead of the location preferred by the Joint Chiefs, Kunsan, 100 air miles south of Inchon. MacArthur had other options, besides Kunsan, which all seemed more prudent, but he stuck to his guns. Indeed, if he had simply introduced more troops into the Pusan Perimeter, or had made the envelopment more shallow, he would not have ended up with the results he achieved: Namely, a complete disruption of the North Korean LOCs and the recapture of Seoul. Instead of simply pushing the North Koreans back or pushing from another side, CHROMITE was designed to completely unhinge the North Koreans and throw them off balance by hitting them from the rear. Only MacArthur’s decision ensured a quick victory without resorting to a slow, bloody series of battles back north up the Korean peninsula, which would have allowed the North Koreans to retreat along their supply lines.

The smashing success of CHROMITE, followed by the recapture of Seoul, coupled with the breakout from the Pusan Perimeter by the Eighth Army, helped the Americans accomplish their principle war aim. The North Koreans were unable to disengage from the American Eight Army units in front of them and reinforce the invasion area. As part of their force was held by Eighth Army, even while withdrawing, North Korean rear area support units were devastated by X Corps. MacArthur’s hammer and anvil technique ensured the virtual collapse of the North Korean army. While the Americans gained their goals, the North Koreans nearly lost everything. In their gamble, they had committed all of their resources, stretching themselves thinly, only to have their logistical tail cut behind them. They retreated rapidly back across the 38 th Parallel, closely pursued by American and ROK units.

MacArthur’s decision to land at Inchon, instead of further to the south as the Joint Chiefs would have preferred, was not only in accordance with the classic fundamentals of war, but more subtly, closely adhered to Clausewitz’s approach. MacArthur realized that he had to make a political statement as well as conduct a military operation. The psychological effect of quickly recapturing the South Korean national capital sent a very strong statement to the rest of the Pacific rim, including China and Russia. CHROMITE was shrewdly designed to signal that America stood by her allies and would come through in a crisis. MacArthur’s adherence to the principles of war is a model for future similar operations:

OBJECTIVE: General MacArthur chose Inchon as the landing site for the amphibious operation primarily because of its proximity to Seoul, the capital of South Korea. Inchon, located on the west coast of the Korean peninsula, is eighteen miles west of Seoul. MacArthur saw the recapture of Seoul as vital for winning the support of the United Nations and for putting fire into the motivation of the Allied Asian countries. Inchon was thus not only a military objective but a political one.

OFFENSIVE: MacArthur saw Operation CHROMITE as the means towards taking the initiative away from the North Koreans. CHROMITE would place the Allied forces on the offensive and gain the decisive momentum required to prevent the war from stagnating and becoming a long, drawn out war of attrition which MacArthur, a veteran of World War One was already familiar with.

MASS: The invasion force, X Corps, consisted of 70,000 troops. Intelligence estimates put the NKPA strength in the Inchon-Seoul area at 8,000 soldiers, of whom 1,800-2,500 were garrisoned in the landing area. This was later confirmed by POWs who stated that the Inchon garrison numbered 2,000. The U.S. Eighth Army, in the Pusan perimeter, was occupying the attention of the NKPA in the south and would keep the North Koreans busy in that sector.

ECONOMY OF FORCE: MacArthur ordered one Marine regiment out of the Pusan perimeter in order to beef up the 1 st Marine Division, X Corps. This was a great risk, but the 1 st Division commander, Major General Oliver Smith, did not feel that he would be able to accomplish the landings without the regiment. When MacArthur reviewed the risk of pulling one regiment out of Pusan, he reasoned that once the landings were successful, the NKPA would withdraw north to counterattack, thus taking pressure off Eighth Army.

MANEUVER: The Americans had the advantage of interior lines at the Pusan perimeter, but were free to exploit exterior lines because of the lack of an opposing naval force. The North Koreans were strung out all along the Korean peninsula with long LOCs. The NKPA was also at a disadvantage because of their terrain induced flanks: the Korean coastline. CHROMITE was designed to be a flank attack with the goal of attacking deep in the enemy's rear, disrupting his LOCs and cutting off the main force's avenue of retreat.

UNITY OF COMMAND: General MacArthur activated X Corps, appointing his Chief of Staff, Major General Edward Almond, as the commander. This was more critical than it appears on the surface because of the very multi-service nature of the Corps. With one Marine Division and one Army Division, a lesser commander might have decided to let each Division commander have his own area, without a single unified command and staff structure. MacArthur’s creation of X Corps for a single mission ensured that he could pick a commander who would follow his guidance to the letter, ensuring mission success, without squabbling over seniority and interservice rivalries. X Corps' sole mission was the Inchon landings and the subsequent capture of Seoul. General Almond understood this, and also knew that once the landings were completed, he was to return to Japan and continue his duties as the Far East Command CofS.

SECURITY: MacArthur realized that operational security of Operation CHROMITE was of primary importance to the success of the landings. Surprise could not be achieved unless the enemy was caught wholly unprepared. Under a cloak of secrecy, X Corps staged out of Yokohoma and Kobe Japan behind a perfect natural screen, Typhoon June and in front of another one, Typhoon Kezia.

SURPRISE: This was achieved partly because of negligible North Korean air and naval capability to gather intelligence on American troop movements. Also, Inchon was not considered the best location for an amphibious assault, by anyone, North Korean or American. Inchon has no beaches, only mud flats. There is also a serious tide problem, with a tidal variance of -.5 feet at low tide and 32 feet at high tide. However, CHROMITE was a complete success. The assault troops encountered only spotty resistance and friendly casualties were much lighter than expected. Within 24 hours of the main landings, the 1 st Marine Division had secured the high ground six miles east of Inchon.

 

SIMPLICITY: CHROMITE was designed to be a single envelopment. X Corps made the amphibious assault at Inchon while the Eighth Army broke out of the Pusan perimeter to tie down and hold the NKPA in place. This prevented the North Koreans from reinforcing their rear areas. The Eighth Army was then to drive north, pushing the logistically cut off NKPA back north, where the Americans would link up with the landing force at Seoul.

 

CHRONOLOGY OF OPERATION CHROMITE:

4 July- Planning conference chaired by MacArthur, who proposes an amphibious assault designed to cut the North Korean Lines of Communication (LOC) at Seoul.

12 August- CINCFE Operation 100-B issued naming Inchon as the target area for the assault.

23 August- Planning conference in Washington, during which MacArthur convincingly presents his case for the assault at Inchon.

26 August- General Order 24 is issued activating X Corps, naming Major General Almond as the commander.

28 August- The Joint Chiefs concur in principle with MacArthur’s plan.

31 August- Lt. Eugene Clark begins his intelligence collection mission at Yonghung-do.

3 September- JTF 7 OPLAN 9-50 issued.

4 September- Air attacks begin against North Korean forces in the Seoul-Inchon area. MacArthur places the 1 st Marine Brigade under X Corps.

6 September- MacArthur confirms earlier orders and announces that D-Day will be 15 September.

11 September- X Corps units, the 1 st Marine Division and 7 th Infantry Division depart from ports in Japan.

13-14 September- The U.S. Navy’s Gunfire Support group arrives off Inchon and begins the bombardment of Wolmi-do Island with air support provided by TF 77.

15 September- D-Day- X Corps arrives at Inchon.

0500: Air strikes hit Wolmi-do Island.

0630: High tide in Inchon harbor.

0633: 3 d Bn, 5 th Marines land at Wolmi-do Island.

0750: Wolmi-do is secured.

1730: High tide in Inchon harbor.

1732: 1 st Marine Regiment lands at Blue Beach, Inchon.

1733: 5 th Marine Regiment lands at Red Beach, Inchon.

16 September- D+1: 7 th Infantry Division begins arriving at Inchon harbor.

0130: Initial D-Day objectives secured.

18-19 September: 7 th Infantry Division lands and moves south of Inchon into a blocking position to protect the beachhead from counterattacks from the south.


BIBLIOGRAPHY

Appleman, Roy E. South to the Naktong, North to the Yalu (June-November 1950). The U.S. Army in World War II. Washington, DC: Office of the Chief of Military History, Department of the Army, 1961.

Doughty, Robert A. The Evolution of U.S. Army Tactical Doctrine, 1946-76. Leavenworth Papers No. 1. Ft. Leavenworth, KS: Combat Studies Institute, U.S. Army Command and General Staff College.

 

Republic of Korea

Chief of Staff

Commander in Chief, Far East

Operations Plan