US Army in World War II
Cavalry and Infantry
by Rich Anderson

Cavalry

Reconnaissance in the armored divisions was performed by the armored reconnaissance battalion -- in the heavy division -- or by the cavalry reconnaissance squadron, mechanized -- in the light division. These units were identical, except that the battalion was organized as companies, the squadron as troops (although the light tank unit was a company in both organizations). In addition, each armored regiment had a reconnaissance company and each infantry division a reconnaissance troop (organized the same as below), while each tank battalion had a reconnaissance platoon.

The mechanized cavalry squadrons were organized with three Cavalry Troops, lettered A to C, each equipped with 13 M8 armored cars and jeeps; an Assault Gun Troop, E, with six M8 HMC; a Light Tank Company, F, with 17 M5 Stuart, or later M24, tanks; a Service Company; and an H&H Company. The armored divisions reconnaissance squadron was identical except that it had a fourth Cavalry Troop, D, and the Assault Gun Troop had eight M8 HMC. Infantry divisions each had a single cavalry reconnaissance troop.

Cavalry groups were usually assigned to corps, but were occasionally attached -- by squadron -- to divisions. Cavalry was primarily intended for reconnaissance missions. However, during the war they were usually employed in defensive, economy of force, security, or screening missions. Armored field artillery, engineer, and tank destroyer units reinforced the cavalry groups for most missions.
 
Interestingly, the cavalry groups were almost never called to perform their primary duty: Later analysis showed that pure reconnaissance missions accounted for only 3 percent of their activities. The remaining 97 percent of missions assigned included: defensive operations (33 percent); special operations "including acting as mobile reserve, providing for security and control of rear areas, and operating as an army information service" (29 percent); security missions "blocking, screening, protecting flanks, maintaining contact between units, and filling gaps" (25 percent); and offensive operations (10 percent).

Thirteen mechanized cavalry groups fought in Europe. They were the 2nd (2nd and 42nd Squadrons); 3rd (3rd and 43rd Squadrons); 4th (4th and 24th Squadrons); 6th (6th and 28th Squadrons); 11th (36th and 44th Squadrons); 14th (18th and 32nd Squadrons); 15th (15th and 17th Squadrons); 16th (16th and 19th Squadrons); 101st (101st and 116th Squadrons); 102nd (38th and 102nd Squadrons); 106th (106th and 121st Squadrons); 113th (113th and 125th Squadrons); and 115th (104th and 107th Squadrons). In addition, the 117th Squadron served with the Seventh Army in Southern France and the 91st Squadron served with the Fifth Army in Italy.
Finally, a number of separate mechanized cavalry troops existed, among them the 56th (which remained in the U.S.) and the 302nd assigned to the 1st Cavalry Division in the Pacific.

In addition to the mechanized cavalry, the US Army fielded a number of horse-cavalry units during the war, including the 1st and 2nd Cavalry Divisions and the 56th Cavalry Brigade with the 112th and 124th Cavalry Regiments (Texas National Guard), and the 26th Cavalry Regiment (Philippine Scouts). Of these, only the 26th Cavalry fought mounted, during the Campaign in the Philippines in 1941 and 1942. The 1st Cavalry Division, the 112th and 124th Cavalry all were sent to the Pacific, where they fought dismounted as infantry. Finally, the 2nd Cavalry Division was originally activated in April 1941 as a racially mixed division, with one 'Colored' Cavalry Brigade and one 'White' Cavalry Brigade. It was inactivated in July 1942 only to be reactivated in February 1943 as a 'Colored' Division. It was sent to North Africa where it was inactivated again in May 1944 with its personnel reassigned to service and engineer labor units.

Infantry

The US mobilized sixty-seven infantry divisions in World War II. They were the 1st-9th, 10th Mountain, 24th-38th, 40th-45th, 63rd, 65th, 66th, 69th-71st, 75th-81st, 83rd-91st, 92nd and 93rd Colored, 94th-100th, 102nd-104th, 106th, and Americal Infantry Divisions, 11th, 13th, 17th, 82nd, and 101st Airborne Divisions, and the 1st Cavalry Division, which was dismounted and utilized as infantry. Forty-two of the infantry divisions and four of the airborne divisions served in the ETO and MTO, the remainder served in the PTO.

The first permanent divisional organization in the U. S. Army appeared in World War I. Nine of these infantry divisions continued to exist through the 1920s and 1930s. These were "square" (two two-regiment brigades) organizations which were replaced, after considerable arguments and field tests, by a "triangular" organization of three regiments. By early 1942 the division was organized substantially the way it would be used in battle, with, in addition to its three infantry regiments, four artillery battalions (three twelve-tube 105mm light battalions and one twelve-tube 155mm howitzer medium battalion), a cavalry reconnaissance troop, and division service troops. A major general commanded the division. A brigadier general was assistant division commander and a second brigadier general was division artillery commander. Colonels commanded the infantry regiments and lieutenant colonels the battalions.

In mid 1944 (TO&E 7, dated 15 July 1943) the infantry division had 18 M3 105mm infantry howitzers, 36 M2 105mm howitzers, 12 M1 155mm howitzers, 5 halftracks, 13 M8 armored cars, 1,371 motor vehicles, and 10 light observation aircraft. Total personnel strength was 14,253.

The infantry regiment was organized with three battalions, twelve lettered companies (A-M, skipping J), an Infantry Cannon Company (first equipped with two halftrack-mounted 105mm howitzers and six halftrack-mounted 75mm howitzers or guns, and later with a towed short-barrelled 105mm howitzer), an Antitank (AT) Company (initially with twelve 37mm and later nine 57mm AT guns), and a Service Company. The fourth company in each battalion (D, H, M) were heavy weapons companies with sustained fire heavy machine guns and mortars. The regiment and each battalion also had a H&H Company. The regimental H&H Company included a Intelligence and Reconnaissance Platoon, the battalion H&H company included an Amunition and Pioneer (A&P, responsible for light engineering duties and for transporting ammunition forward to the line companies) Platoon and an AT Platoon (initially with four 37mm and later with 3 57mm AT guns).

In theory the US infantry regiment of World War II was a powerful, flexible organization and was the core of the infantry division. Unfortunately, poor personnel replacement planning in the early years of the war meant that after a few weeks of combat the regiment was chronically understrength. As an example, on 1 December 1944 the Third Army was understrength in infantrymen by the equivalent of 55 rifle companies. In effect, this meant that on average each of Third Army's infantry divisions were at two-thirds strength in their rifle companies.

The crisis reached a peak in January 1945, when the full extent of the casualties resulting from the Battle of the Bulge were felt. Stringent economy measures and a reorganization of the replacement pool improved matters in February. However, it must be said that the only thing that finally solved the problem was the end of the war.

Besides the standard infantry division, the Army also experimented with a number of specialized divisions. The light division (Alpine Pack or Jungle) and motorized division organizations were not used in combat and were converted to standard infantry divisions. However, the airborne divisions and the mountain division did enter combat.

The airborne division underwent many official (as well as semiofficial and unofficial) changes during the war. As originally conceived they were primarily infantry formations, with two two-battalion glider infantry regiments, a single three-battalion parachute infantry regiment, an airborne engineer battalion, an antiaircraft/antitank battalion, three artillery battalions, and divisional services. Initially, the artillery battalions were all equipped with the M1 75mm Pack Howitzer, which could be parachute dropped or transported by glider. Later, some artillery battalions were equipped with the M3 105mm Howitzer, which was glider transportable.

However, initial combat experience by the 82nd Airborne Division in Sicily and Italy demonstrated that the glider regiments were too weak. As a stopgap remedy, the 401st Glider Infantry was split, with one of its battalions going to each of the 325th Glider Infantry in the 82nd Division and the 327th Glider Infantry of the 101st Division. The other divisions followed a similar process, in the 13th Airborne Division (which never saw combat) the 88th Glider Infantry was disbanded to provide replacements for the airborne forces in Europe and to form a 3rd Battalion for its 326th Glider Infantry, in the 17th Airborne Division the 193rd Glider Infantry was disbanded 1 March 1945 and its remnants were utilized as replacements and to form a 3rd Battalion in the 194th Glider Infantry (both regiments had suffered heavy casualties in the Ardennes in January 1945.

A second augmentation was the attachment of separate parachute units to the divisions. In this way the 501st and 506th Parachute Infantry were attached to the 101st Airborne Division, the 508th Parachute Infantry to the 82nd Airborne Division, and the 507th and the 517th Parachute Infantry to the 17th Airborne Division. Lastly, most of the divisions had a fourth separate artillery battalion attached. Thus, effectively the divisions all (except for the 11th) had four three-battalion regiments and, instead of the 8,596 man strength authorized (TO&E 71, dated 15 June 1943) had an assigned strength of well over 12,000 (17th Airborne, 12,967; 82nd Airborne, 12,921; 101st Airborne, 12,335).

But the 11th Airborne Division in the Pacific followed a unique course. General Swing, commanding general of the 11th, decided to reform the 187th and 188th Glider Infantry, by adding a 3rd Battalion to each and to augment the 511th Parachute Infantry by adding a rifle company to each of its battalions. That was done by utilizing the assets of the 541st Parachute Infantry, which had arrived in the Philippines on 10 July 1945, that regiment being inactivated in August after the reorganization. Unofficially the 187th and 188th were then designated as "Paraglider" regiments by General Swing, who also followed the unique practice of having all elements of the 11ith Airborne cross-trained as both glider and parachute qualified.

The single mountain division formed, the 10th, was created by redesignating the 10th Light Division (Pack, Alpine). The division had been trained in fighting in snow and mountainous terrain and included many famous American skiers and mountaineers, as well as forest rangers and wildlife service men. All were volunteers and the division represented a pool of elite resources that was unique outside of the Special Service Force, Airborne forces, and the Rangers.

The 10th Mountain was organization was similar to an infantry division. However, the division had only three twelve-gun 75mm pack howitzer battalions, a special infantry antitank battalion (with eighteen 57mm guns), the infantry regiments did not have a Cannon Company, and there were only nine 37mm AT guns total in each infantry regiment. Finally, the number of motor vehicles was reduced to 421 of all types, but 5,961 horses and mules were added to provide transportation over rough terrain.
 
In addition to the divisions, there were also a large number of separate infantry, parachute infantry, and glider infantry regiments and battalions. Most of them were utilized as garrisons or for guard lines of communication. For example, only a single separate armored infantry battalions (the 526th) saw combat, the remaining fourteen were disbanded or converted to other units.

Six Ranger battalions (1st-6th) were formed. Three of the battalions, the 1st, 3rd, and 4th, were disbanded in late 1944 after suffering heavy losses at Anzio. The 1st-5th battalions fought in Europe and Italy, the 6th Battalion fought in the Pacific.

The separate infantry units that saw combat service were:

In the ETO; the 3rd, 29th, 65th (Puerto Rican), 118th, 156th, 159th (arrived March 1945 after service in the Aleutians) 442nd (Nisei), 473d (organized by the Fifth Army in Italy on 19 December 1944 from three AAA battalions), and 474th (organized in France on 6 January 1945, with the 99th Battalion and remnants of the 1st, 3d, and 4th Rangers and 1st Special Service Force), and 517th Parachute regiments; and the 1st-5th Ranger, 99th (Norwegian), 100th (Nisei, which in mid 1944 replaced the old 1st/442d which was disbanded -- the 100th retained its original designation), 509th Parachute, 526th Armored, 550th Glider, and 551st Parachute battalions. 

In the PTO: the 4th, 24th Colored, 102d (elements only), 111th, 147th, 158th, 475th (final designation of the 5307th Composite Unit [Provisional], "Merrill's Marauders"), and 503rd Parachute regiments. In addition, the 112th and 124th Cavalry were dismounted and fought as infantry.

One final infantry unit of note was the First Special Service Force (FSSF). The FSSF was organized as a joint U.S.-Canadian unit under the command of the brilliant Colonel (later Major General) Robert T. Frederick. It was designed and equipped for employment in a proposed Allied mission to knock out the hydroelectric power stations of Norway. The Force's men were all volunteers and underwent training for operations in cold climates, snow, and mountains. All became accomplished skiers and mountaineers, and all were extremely physically fit. It acquired a deserved reputation as the toughest and most effective force of its size in the Allied armies, and was, quite possibly, simply one of the best light infantry units ever created.

The Force was organized into three small 600-man strong combat regiments and a 600-man strong Service Battalion. Each regiment contained two small three-company battalions. Each company consisted of three platoons, each with two twelve-man sections led by a sergeant. Each section was equipped with a Browning automatic rifle (BAR), a Johnson light machine gun (not an Army issue weapon, Frederick traded two tons of a new demolition explosive [RS] to the United States Marine Corps for 125 of them), and a Bazooka. Section leaders carried a submachine gun, officers carried carbines, and infantrymen the standard M1 rifle. The companies also each had a 60mm mortar, which were usually allotted one each per platoon. It also appears that some sections were issued flamethrowers. Usually, one man in each section was trained as a sniper. The Service Battalion included an H&H Company, Maintenance Company, Service Company, and Medical Detachment.

Theoretically, the Force included 600 T24 Weasel tracked supply carriers and 1,190 motor vehicles. In practice, the Force only had about 100 Weasels and a few hundred Jeeps (include stolen ones) at any one time.

Airborne Organization, late 1944:

European Theater of Operations
First (Allied) Airborne Army
    XVIII Airborne Corps
        517th Parachute RCT
            517th Parachute Infantry Regiment
            460th Parachute FA Battalion
            596th Parachute Engineer Company
        1st/551st Parachute Infantry Regiment
        509th Parachute Infantry Battalion
        463rd Parachute FA Battalion (75mm)
        13th Airborne Division
            515th Parachute Infantry Regiment
            189th Glider Infantry Regiment
            190th Glider Infantry Regiment
            676th Glider FA Battalion (75mm)
            677th Glider FA battalion (75mm)
            458th Parachute FA Battalion (75mm)
            153rd Airborne AAA/AT Battalion
            129th Airborne Engineer Battalion
        17th Airborne Division 
            507th Parachute Infantry Regiment (attached)
            513th Parachute Infantry Regiment
            193rd Glider Infantry Regiment
            194th Glider Infantry Regiment
                550th Glider Infantry Battalion (attached)
            680th Glider FA Battalion (105mm)
            681st Glider FA Battalion (75mm)
            466th Parachute FA Battalion (75mm)
            155th Airborne AAA/AT Battalion
            139th Airborne Engineer Battalion
        82nd Airborne Division
            504th Parachute Infantry Regiment
            505th Parachute Infantry Regiment (attached)
            508th Parachute Infantry Regiment (attached)
            325th Glider Infantry Regiment 
                2/401st Glider Infantry (attached)
            319th Glider FA Battalion (75mm) 
            320th Glider FA Battalion (105mm)
            376th Parachute FA Battalion (75mm)
            456th Parachute FA Battalion (75mm)
            80th Airborne AAA/AT Battalion
            307th Airborne Engineer Battalion
        101st Airborne Division
            501st Parachute Infantry Regiment (attached)
            502nd Parachute Infantry Regiment
            506th Parachute Infantry Regiment (attached)
            327th Glider Infantry Regiment
                1/401st Glider Infantry (attached)
            321st Glider FA Battalion (75mm) 
            907th Glider FA Battalion (105mm)
            377th Parachute FA Battalion (75mm)
            81st Airborne AAA/AT Battalion
            326th Airborne Engineer Battalion

Pacific Theater of Operations
    11th Airborne Division 
        511th Parachute Infantry Regiment
        187th Glider Infantry Regiment
        188th Glider Infantry Regiment
        472nd Glider FA Battalion (75mm)
        675th Glider FA Battalion (75mm)
        457th Parachute FA Battalion (75mm)
        674th Parachute FA Battalion (75mm)
        152nd Airborne AAA/AT Battalion
        127th Airborne Engineer Battalion
    503rd Parachute RCT
        503rd Parachute Infantry Regiment
        462nd Parachute FA Battalion (75mm)

In the US:

541st Parachute Infantry Regiment
542nd Parachute Infantry Battalion
555th Parachute Infantry Battalion, Colored
464th Parachute FA Battalion