Infantry, Part I: Regular Army /The Korean War

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CMH 60-3: Infantry, Part I: Regular Army
John K. Mahon and Romana Danysh
The Korean War
U.S. Army Center for Military History publication
  • The Korean War

  • When the North Koreans crossed the 38th parallel and invaded South Korea on 25 June 1950, the only U.S. Army personnel in the country were members of the United States Military Advisory Group to the Republic of Korea. The last of the American occupation forces had been withdrawn almost exactly a year earlier, when on 29 June 1949 the final increment of the 5th Infantry Regimental Combat Team moved from Korea to Hawaii. Thus as the war began, the closest U.S. infantry units were the twelve regiments of the 7th, 24th, and 25th Infantry Divisions and the 1st Cavalry Division (organized as infantry), all of which were still on occupation duty in Japan. The first American ground troops to arrive in Korea were the 406 infantrymen of Task Force Smith from the 1st Battalion, 21st Infantry, organic to the 24th Infantry Division, who were flown in from Japan on 1 July 1950. After being reinforced by 134 artillerymen, they met the enemy four days later at Osan in the first American engagement of the Korean War.
  • During July nine of the twelve infantry regiments from Japan arrived in Korea, and the other three arrived in September. The 2nd and 3rd Infantry Divisions, stationed in the continental United States, were also ordered to Korea. Since the 3rd was greatly understrength, one of its organic regiments was replaced by the 65th Infantry from Puerto Rico. In addition to the divisional infantry units, the 29th RCT from Okinawa, the 5th RCT from Hawaii, and the 187th Airborne RCT from Fort Campbell, Kentucky, came to Korea in the first few months of the war.
  • By the end of September 1950, four National Guard infantry divisions had been federalized. The 40th Infantry Division from California, the 45th from Oklahoma, the 28th from Pennsylvania, and the 43rd from Connecticut, Rhode Island, and Vermont brought twelve more infantry regiments into the active Army. The 45th and 40th Infantry Divisions later served in Korea, entering combat in December 1951 and January 1952, respectively. The other two divisions were sent to Europe to strengthen NATO forces. Later in the war, four more National Guard infantry divisions with three organic infantry regiments each were called into Federal service. These units were not sent overseas but remained in the United States. Although three separate RCT's were also federalized during the Korean War, none of the nondivisional infantry regiments from the National Guard served in Korea.
  • As for the Organized Reserve Corps, which was redesignated as the Army Reserve in 1952, its contributions to the Korean War consisted mostly of individuals, not units. An important contribution came from the Reserve Officers' Training Corps (ROTC) program; many of the junior officers who led infantry units in Korea were ROTC graduates. Some small support units were called in, but no Army Reserve infantry regiments were ordered to active duty. They were kept intact and retained as a final reserve in case of an emergency developing elsewhere.
  • By the time the Korean armistice was signed in July 1953, there were ninety infantry regiments in the active Army, almost double the prewar total of forty-six regiments. Meanwhile, separate infantry battalions had increased from thirteen to thirty-one. The number of infantrymen in the active Army grew during the Korean War from 130,554 in June 1950 to a peak of 344,143 in May 1951. In July 1953 the infantry total was 251,685 officers and enlisted men, of whom 146,052 were overseas. They were assigned to units stationed in Germany, Japan, Alaska, Okinawa, Austria, Trieste, Iceland, Puerto Rico, and the Canal Zone, as well as to twenty-three infantry regiments and two infantry battalions serving in Korea.
  • In some ways Korea was a new kind of war for the infantry. The limited nature of the conflict contrasted sharply with the total warfare of World Wars I and II. The United States did not use the atomic bomb and settled for a bitterly negotiated armistice instead of complete military victory. The war was fought in a new geographic area, against new enemies, and for the first time the American infantryman acted as a representative not only of his own country but of the United Nations as well.
  • In spite of these differences, infantry organization during the Korean War was basically the organization adopted after World War II, and infantry weapons used in Korea were by and large World War II weapons.
  • Several organizational changes were made during the war, but there were no striking innovations. As the war progressed, authorized strengths of infantry units were lowered.. The 15 November 1950 TOE strength of the infantry regiment was 3,781, on 15 May 1952 it was 3,662, and by 13 April 1953 it had dropped to 3,531. During that same time period the infantry battalion decreased from 919 to 859 and the rifle company from 211 to 197. These reductions streamlined units by eliminating nonessential personnel in administrative and service positions but kept combat strength high.
  • The internal organization of the infantry regiment, battalion, and company remained almost entirely the same throughout the war. The only major change took place in the heavy weapons company of the battalion and was the result of a new weapon, the 105-mm. recoilless rifle. Although 57-mm. and 75-mm. recoilless rifles had been first used in combat during the last months of World War II and were authorized for all infantry units by the 1 ,June 1945 TOE's, it was too late to permit wide use of the new rifles before the end of the war. Korea, therefore, became the first real testing ground for recoilless weapons. "The infantry's personal hand artillery," as the recoilless rifles were often called, proved to be hard-hitting, accurate, and reliable, and the more powerful 105-mm. recoilless rifle, which had been developed since the end of World War II, was adopted as a standard infantry weapon. In September 1952 the organization of the heavy weapons company was modified to include four of the new 105's, thereby significantly augmenting the company's firepower.
  • Basically, the two new companies added to the infantry regiment in the postwar reorganization remained unchanged during the Korean War. However, several different tank models were used by the tank company, and in the heavy mortar company a new model of the 4.2-inch mortar increased the maximum range from 4,400 to 6,000 yards. The mountainous Korean terrain made employment of tank units difficult, but it was natural mortar country, and infantry mortars of all types (4.2-inch, 81-mm., and 60-mm.) were used extensively. Since the U.N. forces retained control of the air over Korea, there was no special need for improving the infantry's antiaircraft capability. Even the artillery's multiple-fire antiaircraft weapons, the twin-40 and the quad-50, were frequently and successfully employed in ground support of infantry.
  • The organic firepower of the infantry rifle company also increased 'during the Korean War; both the automatic rifles and the light machine guns in the company doubled in number and its 2.36-inch bazookas were replaced by 3.5-inch rocket launchers. The small bazooka was simply not powerful enough to stop the Soviet-built T34 tanks used by the North Koreans and the Chinese Communists. The 3.5-inch launcher, on the other hand, which was rushed into production when the Korean War began and quickly flown to Korea, was credited with knocking out eight T34's on the first day it was used in combat. Described by one infantry officer as "the answer to a rifleman's prayer for a tank killer," the 3.5 was so effective that it was decided not to limit its use to battalion level but to extend it to the rifle company as well. A new TOE dated 15 May 1952 authorized three of these "superbazookas" and placed them in the rifle platoon headquarters. The same table assigned two machine guns to each weapons squad.
  • The nine additional BAR's did not become organic to the rifle company until 13 April 1953, but many infantry units fighting in Korea had used two automatic rifles per rifle squad long before the official TOE change. Although the Chief of Army Field Forces recommended that concurrently with the doubling of the BAR's the rifle squad be increased to eleven men, the strength of the squad remained at nine-at least for the time being. However, the suggestion of an 11-man rifle squad was not completely dropped. It was eventually adopted in the Pentomic reorganization subsequent to the Korean War.
  • The rifle, carbine, submachine gun, and pistol carried by the infantryman in Korea were exact copies of the ones with which he had fought in World War II. Only the carbine was criticized by a majority of the men who used it, since it frequently misfired or jammed both in the extreme cold of the Korean winters and in the dust of the summers. The Ml rifle, on the other hand, was consistently dependable. It remained the basic weapon of the infantry during the Korean War, and contemporary surveys showed that the M I was regarded by the troops "with a liking amounting to affection."
  • The bayonet became more important in Korea than it had been during World War II. It was valued as a morale builder and as a last resort weapon, although most infantry units never fought with it. In general, infantrymen preferred the M4 knife bayonet, issued to men armed with carbines and other weapons, to the M 1 bayonet, which had been authorized for the M 1 rifle by every TOE since 30 January 1945. A knife bayonet, however, was not officially adopted for the rifle until 1 February 1955.
  • Infantry units in Korea had more firepower than World War II units, and their communication and transportation equipment was also much better. Between 1 June 1945 and 13 April 1953 the number of radios in the rifle company increased from 8 to 14 and telephone wire from 2 to 4 miles, while the various trucks and trailers organic to the infantry regiment grew from 243 and 159 to 330 and 223, respectively.
  • A new item of equipment added to the infantry regiment during the Korean War was organic aircraft. Although a November 1945 change to the World War II TOE had given one airplane to the headquarters company of the infantry regiment, it was not included in the April 1948 table. In December 1948 a light aviation section augmentation of five men and two fixed-wing aircraft was provided for nondivisional regiments. Then, in May 1952, a 6-man light aviation section became organic to all infantry regiments and a helicopter, as well as a fixed-wing airplane, was authorized for the first time. In Korea, however, the infantry regiments' aircraft were usually combined with aircraft organic to other elements of the division for centralized operations. Often provisional division aviation companies were organized, although no such units were included in the TOE's. Organic aviation was of great value to the infantry, since it was effectively used for observation, surveillance, and reconnaissance, for quick resupply of weapons and equipment, for transporting commanders, outposts, and patrols over difficult terrain, and-most frequently-for rapid evacuation of the wounded. Successful tactical employment of helicopters was also a big step toward completely airmobile infantry units, which would be capable of moving soldiers quickly into a battle zone and flying them out again after their mission was accomplished.
  • It has been said that no new infantry lessons were learned in Korea, but many old lessons were relearned. The soundness of U.S. tactical doctrine was once again confirmed and no basic changes in infantry tactics were introduced, although the growth of Army aviation foreshadowed the development of the airmobile concept. The Korean War, however, did highlight certain weaknesses in infantry techniques, particularly in such areas as terrain analysis, night operations, patrols, and defensive warfare over an extended front. As soon as these deficiencies became apparent, the Infantry School adjusted its training to include the neglected subjects. The school's activities in general increased a great deal during the war. In the 1949-50 academic year, only 16 classes received tactical instruction at Fort Benning; in 1951-52 there were 118 classes.
  • Since Korean combat experience showed that many infantrymen did not fully understand the triangular concept of organization and its relationship to infantry tactics, General J. Lawton Collins, Army Chief of Staff, directed the infantry School to place more emphasis on these fundamentals in its instruction and publications. In changes dated 2 and 8 December 1952, a paragraph on triangular organization was added to each infantry unit field manual. During the Korean War there was also a renewed emphasis throughout the Army on the basic combat, principles of offensive combat, often referred to as "the Four F's of Fighting"- FIND 'EM, FIX 'EM, FIGHT 'EM, and FINISH 'EM!
  • Not only the regular infantry, but also some of the specialized infantry units that had been organized during World War II fought in Korea. The airborne infantry was represented by the 187th RCT. It participated in two combat jumps, one at Sukch'on and Sunch'on on 20 October 1950 and the other at Munsan-ni on 23 March 1951. Additional combat forces were almost always attached to the RCT for ground operations, and additional transportation had to be attached for any movement required. Artillery support, service units, and particularly antitank defenses were found to be inadequate in airborne operations. Various changes in the composition of the RCT and the organization of the airborne regiment were therefore recommended to correct these shortcomings. In the TOE changes actually adopted during the Korean War, the airborne infantry company's machine guns were doubled, four 105-mm. recoilless rifles were authorized for the battalion's heavy weapons company, and all 2.36-inch bazookas in the regiment were replaced by 3.5-inch rocket launchers. An organic tank company and a larger service company, however, were not added to the airborne infantry regiment until 1954, at which time the number of BAR's was also increased from one to two per rifle squad and from nine to eighteen in each airborne rifle company. Since gliders were not used in Korea and the development of the helicopter made their employment highly unlikely in the future, beginning on 1 January 1953 glider landings were deleted from the capabilities of the airborne infantry.
  • No armored infantry units served in Korea, because the terrain was unsuitable for their employment and there was an absence of heavy enemy armor after the early stages of the war. Several armored infantry battalions were nevertheless activated during the Korean War; some went to Europe, others remained in the United States. No major changes were made in armored infantry organization during this period, but there were some changes in weapons. For example, the .30-caliber heavy water-cooled machine guns were replaced by lighter air-cooled models, the 2.36-inch rocket launchers by 3.5-inch bazookas, and the 60-mm. mortars by 81-mm. mortars. A new armored personnel carrier was also authorized as the basic vehicle for armored infantry.
  • Ranger units, which had fought in World War II and had been dropped from the postwar organization, reappeared during the Korean War. Whereas the World War II rangers had been organized in battalions, the Korean War rangers were organized into separate companies that were normally attached to infantry divisions. All rangers were volunteers, airborne qualified, and specially trained for their mission of infiltrating enemy lines and attacking command posts, artillery positions, tank parks, communications centers, and other key facilities. Since their highly specialized capabilities were not utilized in Korea to the extent anticipated, the ranger companies were inactivated by the end of 1951. Ranger techniques were perpetuated by individual training. In the fall of 1951 a Ranger Department was established at the Infantry School with the goal of providing one ranger-qualified officer per rifle company and one noncommissioned officer per platoon. Starting in July 1954, every newly commissioned Regular Army officer assigned to the infantry was required to take either ranger or airborne training.
  • The elimination of separate Negro units, some of which dated back as far as 1866, was still another change undergone by the infantry during the Korean War. Although both the executive order and the Department of the Army directives on integration had been issued in the late 1940's, the first real application of the new policy came in Korea. On 1 August 1951 the 24th Infantry, the largest Negro unit in Korea, was replaced by the 14th Infantry in the 25th Infantry Division. Personnel of the 24th were transferred to other units, and the regiment was inactivated on 1 October 1951. Other Negro units, including the 3rd Battalion, 9th Infantry, from the 2nd Infantry Division and the 3rd Battalion, 15th Infantry, from the 3rd Infantry Division, were integrated by transfer of personnel and subsequent assignment of replacements without regard to race. By the end of 1951, all units stationed in Korea had been integrated. Originally spurred on by serious personnel shortages and an acute need to increase the combat effectiveness of units in Korea, integration eventually spread throughout the military establishment. As of 30 June 1954, no separate Negro units were left on the rolls of the Army, and all schools and training programs were open without racial restrictions.
  • In addition to Negro units, there had been other infantry organizations in the post-World War II Army made up of different racial and ethnic groups. Several Philippine Scout infantry regiments were among them, but all were inactivated after the Philippines achieved independence and before the Korean War began. There was also the 442nd Infantry, the famous Nisei of World War II, composed of Japanese-Americans; this unit remained in Hawaii on reserve status throughout the war and was not called to active duty. As for Puerto Rican units, Army policy at the outbreak of the Korean War authorized their use only in the Caribbean Command. In September 1950, however, the 65th Infantry (organized with Puerto Rican enlisted personnel) was assigned to the 3rd Infantry Division and sent to Korea to alleviate the major replacement problem. Starting in October 1951, English-speaking Puerto Ricans were made available for assignment on an Army-wide basis and were no longer limited to separate Puerto Rican units or to service in only one geographic area. The 65th Infantry returned to its home island in November 1954 and in 1959 was allotted to the Puerto Rico Army National Guard.
  • Another innovation, caused by the drastic personnel shortages and heavy casualties in the early days of the Korean War, was the integration of 100 South Koreans into each U.S. infantry company. This Korean Augmentation to the United States Army (KATUSA) took several different forms. Some units integrated the Koreans according to the "buddy system" with one U.S. soldier for each Korean, others organized separate Korean squads and platoons commanded by Americans, still others combined both of these methods. Instituted as an emergency measure, KATUSA presented major difficulties to infantry units because of the language barrier, cultural differences, the Koreans' lack of training, and their nonfamiliarity with U.S. Army organization, weapons, and tactics. As American replacements became available, the number of KATUSA soldiers declined and the South Koreans were used to rebuild the Republic of Korea Army, but later in the war when U.S. strength was reduced, an increase in KATUSA personnel was again authorized. The longer the Koreans remained with American units, the more effective they became, and many of the original difficulties were overcome. As a rule, however, they were more successfully integrated into service units than into the U.S. infantry.
  • Although South Koreans and Americans carried the greatest part of the burden, twenty-one other nations also contributed to the U.N. war effort in Korea. Most infantry units from these countries were relatively small, and in combat they were frequently attached to U.S. organizations. As the war progressed, a technique was developed whereby a U.N. battalion was habitually attached to the same American infantry regiment and, in fact, operated as an organic fourth battalion of the U.S. unit.
  • In spite of all of these special infantry organizations, it was the standard infantry that constituted the great majority of infantry units in Korea. Infantry in general played a most significant role in the Korean War. The first American ground troops to arrive in Korea were infantrymen, and all eight U.S. divisions sent to Korea were organized as infantry. As always, the combined effort of all arms and services was necessary for success in Korea, and the infantry depended heavily on their co-operation, particularly on artillery support in the last two years of comparatively static warfare. But, even then, it was the infantry that had the difficult mission of actually capturing the numerous enemy-held hills and outposts. As Lt. Gen. Maxwell D. Taylor, Commanding General of Eighth Army, put it, "the last 200 yards still had to be taken by a determined man on the ground with his rifle and hand grenade." By far the heaviest casualties were suffered by the infantry (out of an Army total of 109,958 casualties, 92,185 were infantrymen), while among the Army's seventy-eight Korean War Medal of Honor winners, seventy came from infantry units.


This work is in the public domain in the United States because it is a work of the United States federal government (see 17 U.S.C. 105).