♦ The Cavalry 1941-45 ♦

The United States Army in World War II


Boots and Saddles: A US Army cavalry trooper, early 1930s (US Army Center of Military History)

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By the mid-1930s the US Army had accepted that the era of the horse cavalry was drawing to a close. It was planned gradually to mechanize the cavalry, replacing horses with tanks, armored cars and other vehicles, and it was in the Cavalry branch that the idea of the armored division first took shape. But lack of money prevented very much from being done. Armored cars and light tanks were procured in limited numbers, but it was not until the beginning of World War II that the desired transformation was commenced.

But on 7 December 1941 the mechanization of the US Army’s cavalry regiments was not yet complete. Those of the Army’s two cavalry divisions were still mounted on horses, while most of the nondivisional regiments were designated horse and mechanized, with one horse cavalry squadron and one mechanized cavalry squadron. The regimental headquarters and service troops  of these regiments were were also mechanized. The nondivisional regiments were considered corps-level reconnaissance units and their horse cavalry squadrons were to be mechanized as the required equipment became available.

The mechanized squadron had a headquarters troop, two reconnaissance troops and a motorcycle troop. The reconnaissance troops’ principal equipment was the M3A1 Scout Car (SC). This was a four-wheel-drive vehicle with light armor and an open-topped crew compartment, armed with one .50-caliber heavy machine gun (HMG) and two .30-caliber medium machine guns (MMG) mounted on a skate rail. Each recon troop had 16 x SC and 23 x motorcycles. The motorcycle troop had 10 x SC and 32 x motorcycles.

The Cavalry Regiment (Horse and Mechanized) was a transitional organization with various deficiencies. The principal one, of course, was the awkward combination of mounted and mechanized sub-units. But the regiment was also deficient in firepower. Except for a motor-towed antitank platoon in the regimental headquarters troop with 6 x 37mm antitank guns (ATG), there were no weapons heavier than the .50 caliber HMG. Nor did the M3A1 SC prove itself entirely satisfactory. Its off-road performance was indifferent, and with its thin armor and open-topped crew compartment the M3A1 was vulnerable even to small-arms fire and grenades. Thus when the regiments were fully mechanized in 1942-43, a number of changes were made.

Guidon of Headquarters & Headquarters Troop, 3rd Cavalry Regiment

The Cavalry Regiment (Mechanized), whose table of organization was approved in April 1942, had four reconnaissance troops, two support troops and a regimental service troop. The two squadron headquarters troops were reduced in size, some of their assets being reallocated to the recon troops. They now functioned purely as tactical headquarters to which recon and support troops could be assigned according to mission requirements. This organizational scheme was somewhat similar to that adopted for armored divisions: two combat command headquarters controlling a variable number of sub-units as required.

The recon troops had a headquarters platoon with 3 x SC and three recon platoons each with 2 x SC, 2 x 37mm ATG and 1 x 81mm mortar, for a troop total of 9 x SC, 6 x 37mm ATG, and three 81mm mortars. The two support troops each had three tank platoons, each with with 5 x M5 light tanks (37mm gun) and a self-propelled assault gun (SPAG) platoon with 3 x T30 halftracks mounting a 75mm howitzer. Throughout the regiment, motorcycles were largely replaced by halftracks and 0.25-ton trucks: the ubiquitous Jeep. The revised organization and the addition of tanks, additional ATG and mortars enhanced the regiment’s tactical flexibility and considerably augmented its firepower. The retention of the M3A1 SC was something of a drawback, but a replacement, the M8 Armored Car (AC) was already in production.

As things turned out, however, the April 1942 organization did not last long enough for all cavalry regiments to undergo conversion. In early 1943 the Army decided to abolish the regiment as a tactical unit in all branches except Infantry. Its replacement was the group: a headquarters unit to which independent sub-units could be attached as required. For the existing regiments of the Cavalry branch the changeover was accomplished as follows (using the 4th Cavalry Regiment as an example). The regimental headquarters troop became Headquarters and Headquarters Troop (HHT), 4th Cavalry Group (Mechanized); the 1st Squadron became the 4th Cavalry Reconnaissance Squadron (Mechanized); and the 2nd Squadron was renumbered as the 24th Cavalry Reconnaissance Squadron (Mechanized). In principle these were all independent units, though in practice the two squadrons were attached back to the group and usually stayed with it. The cavalry group, like the cavalry regiment it replaced, was a nondivisional unit, assigned at corps level. But armored and infantry divisions also had mechanized cavalry units: a squadron for the former and a reconnaissance troop for the latter.

December, 1944: M8 armored cars on the move during the Battle of the Bulge (US Army Center of Military History)

The new separate Cavalry Reconnaissance Squadron (Mechanized) had an HQ troop, three reconnaissance troops, a light tank troop and an assault gun troop. The squadron for armored divisions was in most respects identical to the squadrons attached to cavalry groups, but it had four rather than three reconnaissance troops and a fourth platoon in the assault gun troop. The separate reconnaissance troop for infantry divisions was identical to those in squadrons. By 1944 the M3A1 SC had replaced by the M8 AC, and the T30 halftrack SPAG had been replaced by the fully tracked M8. This latter vehicle was based on the M5 light tank, with a 75mm howitzer in an open-topped turret. The light tank troop was equipped with the M5A1 Stuart light tank, armed with a 37mm gun and three .30-caliber MMG.

The basic mechanized cavalry unit was the Cavalry Reconnaissance Troop (Mechanized). It consisted of a headquarters section and three platoons, each with an armored car section and a scout section. The former had 3 x M8 AC; the latter had 6 x Jeeps, 3 x .30-caliber MMG and 3 x 60mm mortars. In total the troop had 12 x M8 AC, 3 x .50-caliber HMG, 13 x .30-caliber MMG and 9 x 60mm mortars. The Light Tank Troop had 17 x M5A1 light tanks and the Assault Gun Troop had 6 x M8 SPAG. Thus by 1944 the Army’s mechanized cavalry units were highly mobile and well armed, though the combat experience acquired between D-Day and VE Day disclosed some lingering deficiencies.

Though the M8 AC was an improvement over the M3A1 SC, its off-road performance was even less satisfactory than the vehicle it replaced. Though its 37mm gun was capable of destroying any German reconnaissance vehicle, the M8 was vulnerable to the 20mm guns with which the latter were mostly armed. On the other hand, the M8’s on-road performance was exceptional, its six-cylinder gasoline engine giving it a top speed of 55 mph. The engine also ran quietly, a desirable feature in a reconnaissance vehicle. Finally, the fact that it was wheeled rather than tracked meant that the M8 was easier to maintain than its stable mate, the M5A1 light tank.

Like the M8, the M5A1’s main armament was 37mm gun — which by 1944 was marginally effective at best against German tanks. It could damage a Panzer IV, but against a Panzer V (Panther) or Panzer VI (Tiger) tank the 37mm gun was hopelessly inadequate. One solution was to attach a medium tank company or a self-propelled tank destroyer company to the cavalry group, but these were not always available. A replacement for the Stuart light tank had been in development since mid-1943: the M24 Chaffee. Though lightly armored, the Chaffee was armed with a 75mm gun—a vast improvement over the puny 37mm. M24s began to reach the cavalry in late 1944, but only a handful saw action before the war came to an end.

The M5A1 Light Tank as depicted in a wartime US Army technical manual

During the campaign in northwest Europe, each US corps usually had a cavalry group attached, and others were held at army level. During the Battle of the Bulge many cavalry units were heavily engaged in defensive fighting for which they had never been intended, and suffered heavy casualties. The cavalry played a prominent role in the last offensive into Germany and postwar several cavalry groups were incorporated into the United States Constabulary. The Constabulary was an Army command responsible for maintaining law and order in the American zone of occupied Germany pending the reconstitution of a German police force, and performed this duty until 1952.

The lessons learned through the mechanization and reorganization of the cavalry and its combat employment in World War II led eventually to the development of the Cold-War-era Armored Cavalry Regiment, which integrated armor, mechanized infantry, field artillery and helicopters in a potent combined-arms team.

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Organizational Diagrams




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