General MacArthur and Operation Chromite

Operation Chromite
The operational environment consisted of North Korean forces advancing to the Pusan Perimeter so as to surround it. North Korea had just conquered Taejon and was moving in the direction of the UN’s position, causing American forces and South Korean forces to retreat.
The dire situation facing the U.S. Eighth Army at the Pusan Perimeter was exacerbated by a steady decrease in strength that had continued since the conclusion of WW2: “Army forces consisted of four understrength divisions equipped with worn-out weapons from WWII.”[footnoteRef:1] The Army was using out-dated weaponry and the U.S. Eighth Army experienced logistical challenges due to the Korean landscape and air interdiction. Additionally, the Eighth Army was full of young men who had never experienced combat, had little training, and possessed inadequate heavy artillery.[footnoteRef:2] [1: Operation Chromite, II-1.] [2: Operation Chromite, II-1-2.]
General MacArthur’s vision for Operation Chromite relieves NKPA pressure on the U.S. Eighth Army in the Pusan Perimeter by sending new units into the battle as they became available for action. MacArthur’s use of amphibious operations and joint operations ensured that a complete defense and shift to offense could be conducted, and that is what put the NKPA in a defensive rather than in an offensive position. This in turn allowed the Eighth Army to prepare itself accordingly and set about reestablishing its position at the Perimeter.
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General MacArthur’s vision for the operational environment once Operation Chromite was concluded (the end state) consisted of capturing Inchon and allowing the UN forces to retake Seoul. The end state was thus characterized by the U.S. Eighth Army’s taking control Inchon and supporting the takeover of UN troops in Seoul. The four point strategy employed to achieve this objective was to attack the rear of the NKPA and harm the enemy’s supply lines to the south, while threatening the NKPA’s capital at Pyongyang and leveraging political capital in the South by reasserting sovereignty in Seoul. These four decisive actions were designed to send the message to the NKPA that it was useless to wage a conflict with the South as this was tantamount to starting a conflict with the West, in which case it stood no chance of surviving if it did. The bulk of the vision, however, rested on taking Inchon via amphibious assault as a joint operations exercise. This was the first step in the vision as Inchon would serve as the base or foundation for the next step—the advance on Seoul and the severing of the lines of communication and supply of the enemy.
The plan for Operation Chromite was to make use of amphibious assault to take Inchon: “The plan called for X Corps (to be formed around the 1st Marine Division and the 7th Infantry Division) to execute a phased amphibious landing at Inchon.”[footnoteRef:3] The assault was planned and supported by joint operations and Marines and support from the air were available to assist in the landing. Once Inchon was taken, X Corps would head inland to take Seoul and cut the enemy’s communications and supply lines that were supporting the NKPA’s forces in the south. JTF 7 was there to assist in the landing by giving support to secure the area surrounding Inchon and the total effect of this joint operations approach was that the Eighth Army was completely supported. [3: Operation Chromite, II-6.]
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As JP-5 notes, a key decisive point is a major event or factor (such as a turning point in strategy) that allows one to obtain an advantage over one’s enemy when enacted. As stated in the Joint Task Force Command and Control guide, “a commonly shared dynamic visual representation and associated Global Command and Control System (GCCS) data management tools can be used to integrate and manage relevant data sources” which will help a commander and his staff to identify decisive points.[footnoteRef:4] Two key decisive points for Operation Chromite were: 1) the use of asymmetric action—i.e., the joint operations involving UN sea and air combat power directed at the land forces of the NKPA, and 2) MacArthur’s vision which included a clear expression of goals and the way in which those goals could be achieved. The first of these key decisive points included understanding the vulnerabilities and weaknesses of the enemy and then planning joint operations attack that would focus on that vulnerability. By exploiting the enemy’s weakness, the U.S. was able to take what seemed like a strong offensive position to the NKPA and turn it into a weak, defensive position. As the NKPA could not operate in both the air and sea, as the UN and US forces could, it was at a significant disadvantage. [4: JP 3-33, IV-5.]
The second of these key decisive points included MacArthur personally assessing the situation, using his past experience and knowledge to plan a decisive operation that would use the data from the field and apply the strengths of the Western forces to the weaknesses of the NKPA. By personally assessing the environment and drawing upon his knowledge of how joint operations could allow the UN and U.S. forces to turn the tables on the enemy, MacArthur set about creating a vision for these same UN and U.S. forces, by getting a firm sense of the terrain and what was required. Then MacArthur provided clear and coherent goals supported by a strategic course of operations that was implementable and effective.
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First, Operation Chromite reversed the situation at the Pusan Perimeter, and second, it placed the Allied forces in an advantageous position over the NKPA. The operation allowed for the breakout of the U.S. Eighth Army at the Pusan Perimeter and did this through reversing the course of action and then putting the Allies in a better position to win. The reversal maneuver came about after the failure of the air interdiction against the NKPA to impact the movement of the enemy. MacArthur turned to an amphibious joint operation that allowed the Allies to take Inchon, which was an important decisive point in the battle.
The second maneuver which allowed the Allies to obtain an advantage over the NKAP was the joint operation sea and air attacks against the NKAP, which resulted in cutting the supply line of the enemy and forcing the enemy to abandon its gained ground. This opened the path to retaking Seoul, and with the enemy’s supply line and communications line severed, the NKPA was in a weakened position and not disposed to prolong a conflict with the south or with the Allies. Thus, by first securing a foothold at Inchon through joint operations and then by attacking the enemy’s vulnerabilities, the Allies gained an advantage in the war. This was the asymmetric action that the NKPA simply could not copy: that is why “throughout the campaign, the advantage of being able to operate in the air and at sea, where the enemy could not, was important to success.”[footnoteRef:5] [5: Operation Chromite, II-11.]
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Joint Fires will support Operation Chromite for (1) landing forces at Inchon by providing protection against return fire from the enemy. It would provide support for (2) attacking the NKPA’s communications and supply lines by allowing the Allied forces to advance on their way to Seoul in spite of any retaliatory measures taken by the enemy. The Joint Fires support in severing the enemy’s lines would come by way of pinning down the enemy and cutting its lines in two so that the NKPA could not effectively regroup. Joint Fires would support interdicting any NKPA attempts to counterattack or reinforce forces as an element within the overall organization of the defense of the Allies in providing security for the advantage gained in Seoul: “An element is an organization formed around a specific function within a designated directorate of a JFC’s HQ. The subordinate components of an element usually are functional cells. An example of an element is the joint fires element.”[footnoteRef:6] This Joint Fires element contributed to the support of the operation by providing cover for the ground forces as they took Inchon and then headed inland to Seoul. [6: JP 3-33, II-12.]
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The other Services (Air Force, Marines and Navy) provided General MacArthur with operational reach in Operation Chromite by contributing air, land and sea power to the fight against the NKPA. By operating in all three spheres, the Allies were able to leverage their power against the enemy, secure territories, exploit the enemy’s weaknesses, turn the tide of the war, and gain the advantage by taking Seoul. Making use of all the tools available to him, MacArthur effectively developed and implemented a strategy that was devised around the usage of these tools—i.e., the joint operations of the various military branches to ensure victory.
The operational reach provided an advantage to the Allies over just reinforcing the Eighth Army inside the Pusan Perimeter by providing support for securing the region from the air and from the sea, keeping communication and supply lines open for the Allies while closing them for the enemy, and providing a continual stream of reinforcements and better weaponry when needed. One example of this is that the 3rd Battalion, 5th Marines involved in the landing force operation at Inchon, “made the initial assault on Wolmi-do with the high tide at dawn on 15 September and crushed enemy resistance.”[footnoteRef:7] Only after surveying the tides and the area and making sure this approach would work was the operation executed—and that depended on excellent communication, due diligence in reconnaissance of the field of operations, and a combined effort among the various branches. [7: Operation Chromite, II-9.]
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General MacArthur’s staff used (1) simultaneity when the 1st Marine Division drove inland from Inchon to Seoul and the Eighth Army supported this drive with an attack of its own. The Eighth Army linked up with X Corps forces just south of Seoul in a simultaneous attack with the Marines against the NKPA. This simultaneous approach helped to overwhelm the NKPA.
General MacArthur’s staff used (2) depth in executing the amphibious landing. There were only a number of days during the year when the channel was sufficiently deep to allow large craft to use the water lanes.[footnoteRef:8] By analyzing the availability of this channel and ensuring its usability, the staff showed depth of execution and diligence in reconnaissance. [8: Operation Chromite, II-9.]
General MacArthur’s staff used (3) timing in executing the counter-attack on the NKPA by coordinating assaults so that they would coincide with one another and with the environmental conditions of the region. This allowed them to take the enemy by surprise and gain them the advantage.
General MacArthur’s staff used (4) tempo in executing Operation Chromite. By pushing the forces, from the Marines to the Eighth Army to the X Corps and so on, the Allies never let up and never allowed the NKPA an opportunity to regroup and regain their balance. The relentless march and drive with which the operation was conducted once it was initiated allowed the joint operations forces to be successful in taking the momentum away from the enemy.
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General MacArthur used the Dislocate defeat mechanism to defeat the NKPA by dislocating the enemy from its supply and communication lines. Without these, the enemy was essentially cut adrift from its foundation and was like a rudderless ship at sea with no anchor or tie to the shore. Dislocated from its main base of support, the enemy had no choice but to retreat and surrender the territory it had gained. Thus, MacArthur identified the main weakness of the enemy and then effected a strategy of hitting the enemy at this very point. Stretched out and thin, the enemy could not effectively respond to the dislocation.
General MacArthur used the Isolate defeat mechanism as well to defeat the NKPA by isolating the enemy’s land forces from any aerial bombardment or amphibious assault. The aim of this mechanism was to wedge the enemy in between two collaborative forces of power (air and sea) while a third force (land) directly attacked the isolated enemy’s troops.
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General MacArthur used a joint approach in attacking the NKPA because this is what is demanded of modern warfare. The synergy of forces among the Allies along with the amphibious assault with air, land, and sea power to support the attack at Inchon and Seoul, allowed MacArthur to drive the enemy from its gained ground and enact a strategy of dislocation and isolation. Without the joint approach applied, the NKPA would not have been dealt with so forcefully, their supply and communication lines would not have been cut, and the Allies would not have been able to take Inchon and Seoul in a simultaneous drive.
MacArthur chose the joint operations approach because in modern warfare there is a need for synergy of forces.[footnoteRef:9] With forces operating on their own, they have a limited scope and ability to confront the enemy from a strategic standpoint that will ensure neutralization of the enemy combatant’s forces and support network. A synergistic approach (joint approach) allows for multiple forces to combine in an effort to provide full-spectrum assault capabilities on an enemy that will render the enemy incapable of a response. [9: Operation Chromite, II-15.]
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Risk 1:
Geography of the landing at Inchon was tough and would lead to loss of life.
Mitigation:
A three man team was used by the Navy to identify enemy defenses at the landing. This helped reduce the risk of loss of life as the Allies would know from where to expect fire.
Risk 2:
The tide at the landing might not be favorable and would lead to forces being easily picked off by the enemy
Mitigation:
The same Navy team was sent to study the tide. The team verified that the tide was accurate and would support the landing.


Risk 3:
The landing at Inchon would meet difficult terrain challenges that could lead to loss of life.
Mitigation:
The USN and ROK civilians lighted the way on the terrain at night to guide the forces. This helped the Allies see a navigable path at Inchon.
Risk 4:
Amphibious landings are complex and almost anything can go wrong that will end in disaster and substantial loss of life.
Mitigation:
The JTF would plan the operation, isolate the landing site, secure the area, and provide air and fire support. Heavy naval bombardment support would also be available.
Risk 5:
The enemy could oppose the amphibious landing from the land.
Mitigation:
Aerial bombardment would be supplied. The TF 91 would also provide support so that landings could be secured.