A potentially major threat to the US operation was the Soviet-built T-34/85 tanks of the North Korean People’s Army 105th Tank Division. In the march from Inchon to Seoul, 53 of these lethal machines were thrown into counterattacks against the Marines. These tanks had been extremely effective combat vehicles against the best German armor in World War II just five years before. They also furthered their reputation in the first weeks of the North Korean invasion. However, after the initial encounter, the Marines were completely nonplussed by their arrival on the battlefield. They were easily destroyed by a combination of Marine close air support, Marine M-26 tanks, and antitank weapons. By the time the Marines secured the west bank of the Han River, 48 had been knocked out by the Marines and five were found abandoned. In the battle for Seoul itself, the 1st Tank Battalion destroyed 13 T-34 tanks or Soviet-built self-propelled guns and 56 antitank guns, for the loss of five Pershing tanks and two Shermans (most of the American tank losses were to mines and at least one was lost to one of the frequent attacks by North Korean sappers armed with satchels of explosives). Importantly, North Korean armor was of sufficient strength that it could have completely disrupted the US operation, had the US not enjoyed close air and armor support. Thus, armor and close air support were again proven to be very important factors to successful urban combat.
The relatively small size of the US attacking force was possible due to effective air, naval, armor, and artillery support. The air support of the Marines in the Inchon-Seoul operation was particularly effective and noteworthy. Marine aviation units perfected the art of close air support during the Korean War, beginning in the Inchon–Seoul battles. That support was far more responsive and closely coordinated than that achieved by the Marines in World War II. Six Marine squadrons (four day-fighter and two night-fighters) supported the 1st Marine Division and X Corps during the operation. They were controlled by the 1st Division’s 1st Marine Air Wing. They had no other mission other than close air support of the ground forces. Initially the Marines flew in support from two navy escort carriers, the USS Badoeng Strait and the USS Sicily, but once Kimpo airfield was captured, the five F4U Corsair squadrons and the one F7F Tigercat squadron operated from that base, literally minutes from their targets. Close air support was coordinated by Marine Tactical Air Control Squadron 2, which commanded tactical air control parties (TACP) located in each Marine infantry regiment and battalion headquarters. When the US Army 32nd Infantry Regiment entered the battle for Seoul, a Marine TACP was attached to the regiment to give it the benefit of close air support. During the 33-day campaign, September 7–October 9, the Marine aviation units flew almost 3,000 ground-support sorties, including over a thousand in support of the Army’s 7th Division.
Aviation support was critical to the advance from Inchon to Seoul. It was particularly critical to the 5th RCT’s difficult attack south on the east side of the Han River. However, once units entered the city proper the use of close air support became increasingly difficult because of the difficulty of identifying the front line from the air and the danger to the friendly civilian population. Still, even as the battle raged inside Seoul, close air support played an important role aiding the advance of the 7th Marine Regiment through the mountains north of Seoul, isolating the city from reinforcements, and destroying KPA units attempting to retreat from the city.
Politics and Urban Warfare
One of the major characteristics of the fight for Seoul was the intense pressure put on the Marine division to capture the city quickly. This pressure was resented by the Marine officers because speed often caused them to take risks with the lives of their Marines. Often this was viewed as General MacArthur placing politics before the tactical considerations of urban combat. However, there were good reasons to take the city quickly. First, the military advantages of cutting off the bulk of the KPA south of Seoul were obvious. Second, and perhaps most important, were the psychological and political advantages to be gained by recapturing the city less than three months after its capture by the KPA in June. The capital of Seoul defined the allied government of the Republic of Korea and restoring that city to allied control was extremely important strategically to the prestige and legitimacy of the South Korean government. MacArthur understood how strategic Seoul was to the South Korean government, as well as to the UN cause and to the US home front, which desperately needed positive war news. Thus, like many important capital cities in warfare, the strategic value of the city was worth the tactical sacrifices necessary to capture it, and capture it quickly.
Another characteristic of the battle for Inchon–Seoul was the integration of South Korean forces into the battle. There is no doubt that South Korean forces were not necessary to the battle. However, General MacArthur insisted that the ROK Marine Regiment and the 17th ROKA Infantry Regiment be integrated into operations and participate in the recapture of Seoul. Again, this insistence demonstrated that the fight for a capital city such as Seoul was as much about perceptions and information operations, as it was about tactics. The role of ROK infantry and Marines in the battle was small, but the prestige incurred by the ROK government was huge, and the battle did much to boost the morale and confidence of the ROK military which eventually would assume the largest burden of combat operations in the war and would prove itself capable of fighting not just the KPA, but also the Chinese Army effectively.
A final characteristic of the campaign for Seoul and the battles for Inchon and Seoul was the nature of the assaulting force. The assault force, X Corps, was a unique organization. Though its composition was strongly influenced by the lack of available forces in the early days of the Korean conflict, it was also uniquely tailored to the needs of modern urban combat. The X Corps was a true joint-service force, and a combined allied force, and thus had capabilities not found in a typical army corps. As a joint force it had unique amphibious, naval support, and close air support capabilities which were all critically necessary to the strategic situation, and the tactical problems involved in the recapture of the Korean cities. The leveraging of the capabilities of air and naval power reduced the need for large numbers of infantry, and reduced the casualties among the attacking US and ROK Marines and infantry. The navy ensured strategic surprise and supported the force logistically, and with naval gunfire. The air component augmented artillery fires, protected the force from North Korean airpower, and helped isolate the urban battlefield. Both air and naval forces provided a psychological boost to the assaulting US and ROK Marines and infantry, and demoralized the KPA defenders. As a combined US and ROK force, X Corps represented the unique political nature of the Korean conflict, and maximized the strategic gains that the recapture of the ROK’s capital represented. Neither a single-service corps, nor a completely American corps, could have conducted the operation as effectively, or achieved the same strategic success that the uniquely joint and combined allied X Corps was able to achieve. In many ways X Corps represented an ideal urban fighting organization.