Tank destroyer battalion (United States)

In April 1941, a conference focused on the future of antitank operations. The immediate effect was to create an anti-tank battalion in infantry divisions, but this organic anti-tank capacity was not deemed sufficient. The conference gave broad support to the idea of creating mobile anti-tank defensive units (commanded by corps or army formations) which could be deployed to meet an armored attack. The effort stalled on the issue of which branch of the Army should control it—the infantry (as a defensive role), the cavalry (as a mobile response force), or the artillery (as heavy guns). The Armor Branch did not press for control of the anti-tank units, feeling that it would be at odds with their general principles of maintaining the offensive. In May, General George C. Marshall "cut through the knot" by declaring the issue as sufficiently important to be dealt with as a combined-arms organization, forming an Anti-Tank Planning Board headed by Lt. Col. Andrew D. Bruce, and appointing Brigadier General Lesley J. McNair to take immediate action on organizing anti-tank forces. Three anti-tank "groups" were quickly organized, with each of three anti-tank battalions drawn from infantry divisions and various support units, and tasked with "speedy and aggressive action to search out and attack opposing tanks before they had assumed formation".[1] In August, a plan was laid out for a program of 220 anti-tank battalions.[lower-alpha 1]

The first nine units were deployed during the Louisiana Maneuvers of 1941, equipped with towed 37 mm M3 anti-tank guns (the largest gun that could be towed by a jeep) and surplus 75 mm M1897 guns mounted on half-tracks (the M3 Gun Motor Carriage), and again in the Carolinas maneuvers that November. Their employment was judged a success—though not without some disgruntled voices in the Armored Branch arguing that the umpires had rigged the results[2] — and on 27 November, Marshall ordered the establishment of a tank destroyer Tactical and Firing Center at Fort Hood, Texas, under Bruce, and the activation of 53 new anti-tank battalions under the command of General Headquarters. The term "tank destroyer" was used from this point on, as it was seen as a more psychologically powerful term. On 3 December, all existing anti-tank battalions were reassigned to General Headquarters and converted to tank destroyer battalions. The new tank destroyer doctrine was formally stated in Field Manual 18–5, Tactical Employment, Tank Destroyer Unit, in June 1942. It laid down a focused doctrine— "There is but one objective of tank destroyer units… the destruction of hostile tanks" —and repeatedly emphasized an offensive, vigorous spirit. Tank destroyer units were expected to be employed as complete battalions, held in reserve and committed at critical points, rather than parceled out as small defensive strongpoints. The emphasis was heavy on mobility, and the ability to outmaneuver the attacking armor; this would feed into vehicle design, and cause the speed of a vehicle to be prioritized over survivability.

One side-effect of the new status of the tank destroyer force was that, as a fully-fledged independent branch, it was required by War Department policy to establish units manned by African Americans – the United States Army remained racially segregated until the Korean War, but the War Department placed pressure on the Army to ensure that a fair proportion of combat units were black. Two of the initially converted battalions were black, with another four created in 1942 and four (of a planned six) in 1943. Several would eventually see combat, and the 614th Tank Destroyer Battalion would become the first black unit to receive a Distinguished Unit Citation.[lower-alpha 2][4]

Basic US Tank Destroyer doctrine: German armor breaks through US lines. A tank destroyer battalion responds by moving into the path of the advance. The units then position themselves to fire at the advancing tanks from hidden positions.

US tank destroyer doctrine was essentially a defensive and reactive measure. Their role was to slow down, or even stop, a Blitzkrieg style armored thrust and prevent it from penetrating too deeply or from encircling friendly forces in a pincer movement. The idea was that, once an enemy armored thrust was expected to break through, the tank destroyer battalion (as a single unit and operating behind the front lines), would position itself to intercept the enemy while a more complete defense is organized at corps or higher level. This was to be the case for both towed and mobile tank destroyer battalions. As the enemy armored thrust approached, organic reconnaissance units would communicate to battalion commanders the best locations for tank destroyer units to place themselves in, while organic pioneer units would create blockades or help the tank destroyers dig into their positions. As the enemy armored thrust came within range, the hidden tank destroyer units would fire upon enemy tanks and then retreat to another position once they began to draw fire.

In the offense, mobile tank destroyers were not given the duty to hunt down enemy tanks,[lower-alpha 3] as this would be the role of their own tanks. Instead, they were to be positioned close to the advance to stop any counter-attacking armored force.[6][lower-alpha 4] Towed tank destroyer units had no offensive role in an armored thrust, and were given the task of supporting infantry units or being used as indirect fire units to augment artillery. Mobile tank destroyers were also allowed to support infantry operations, or even function in an indirect fire role, so long as their main mission was not compromised.

In terms of vehicle design, mobile tank destroyers were to be heavily armed, but with speed given priority over armor protection. Unlike tanks, mobile tank destroyers were not designed to survive hits from enemy AP rounds, but to mainly resist small arms fire. Crews were also trained to hide their vehicle from enemy fire.

The Reconnaissance company of the tank destroyer battalion was made up of three reconnaissance platoons and one pioneer platoon, along with supporting units.

The reconnaissance platoons had two main missions for the battalion's tank destroyer units: "Route reconnaissance, particularly of those routes over which the gun companies will move to reach combat areas", and "Area reconnaissance, particularly to locate general areas suitable for use as combat areas by the gun companies".[12] Other missions included zone reconnaissance, battle reconnaissance, security missions and counter-reconnaissance.[lower-alpha 5] Each platoon had two M8 Greyhound armored cars and five 1/4 ton trucks (jeeps). In the context of Tank Destroyer doctrine - that the battalion be placed in the path of an enemy armored thrust - the reconnaissance platoons served to seek and locate areas for tank destroyer units to set up.

The pioneer platoon had two general missions: to prevent the movement of the battalion from being delayed by natural or artificial obstacles, and to impede or canalize the movement of the enemy by the creation of obstacles. The pioneer platoon consisted of a platoon headquarters and two sections, each section included ten men and two 1+1⁄2-ton trucks equipped with pioneer tools and equipment; the platoon headquarters consisted of six men, an M20 armored utility car (a variant of the Greyhound), and an air compressor (MT2) complete with all its various air powered tools.[13]

Since neither the pioneer nor reconnaissance units were able to function as originally intended (see below), they were often attached to other units (such as engineering battalions or cavalry reconnaissance squadrons) that operated under the division or corps that the tank destroyer battalion had been assigned to.

The M3 Gun Motor Carriage (M3 GMC), which mounted a 3-inch gun on a half track, was the first effective mobile US tank destroyer.

During the Tunisian Campaign of 1942–1943, the US forces would employ seven tank destroyer battalions.[lower-alpha 6] However, contrary to doctrine they were invariably broken up down to the platoon level to support infantry units. On the one occasion where a tank destroyer battalion was employed as an organized unit—the 601st, at the Battle of El Guettar—it defended against an attack by the 10th Panzer Division, destroying 30 of its 57 tanks.[lower-alpha 7] This engagement had the distinction of being the only time a battalion would fight in the way envisaged by the original "tank destroyer" concept, as an organized independent unit opposing an armored force in open terrain. The 601st lost 24 of its 36 M3 Gun Motor Carriage (GMC) tank destroyers.[15] Seven M10 tank destroyers from the 899th tank destroyer battalion were also lost in the battle.

Critical analysis of the new force was mixed; while the 601st had successfully repulsed the attack, it had lost two-thirds of its strength in the process, contributing to Major General George Patton's declaration that the concept was "unsuccessful in the conditions of the theater".[16] McNair responded by further clarifying the role of the tank destroyer—it was to be a highly mobile force, which sought to find and occupy favorable positions to engage an oncoming enemy attack. A tank destroyer "need only to maneuver for a favorable position, conceal itself thoroughly and ambush the tank"[16]—it was not intended to be used in a frontal offensive, or in assault in combat like a tank.

Training problems were also exposed. Mobile Tank Destroyer units had not been trained to work together as a battalion - despite the doctrine being so clearly to the fore, actual training of the units was done at a small unit level. Also at issue was the performance of the organic reconnaissance units, who had never experienced such extended distances in training as they were forced to operate in North Africa. With an inability to work together as a battalion, along with the poor performance of the organic reconnaissance units, many vehicles were lost in the Battle of El Guettar.[17]

Major changes to the overall doctrine emerged from the North African campaign.

Flaws had emerged in the M3 GMC and M10 tank destroyers—they were not fast enough, and had an overly high silhouette which made them vulnerable to direct enemy fire. Major General Omar Bradley, then commanding the U.S. II Corps in North Africa, suggested that towed anti-tank guns could be reintroduced to infantry units—while it was feared this would lead to a lack of offensive spirit, it was undeniable that a small towed gun could be dug in very quickly and efficiently, giving a very low-profile target, though a large gun sometimes took a day to fully prepare. Bradley's proposal was not, however, intended to create towed TD battalions. His intent was to put the anti-tank assets in the hands of infantry units. The fact that the British Army had had success with dug-in antitank guns supported his proposal, and an experimental battalion was established in the summer with 3-inch guns. This quickly gained popularity—heavily supported by McNair—and in November 1943 it was ordered that half of all tank destroyer battalions were to be equipped with towed guns; this was a major distortion of Bradley's suggestion.

The expected employment of the battalions shifted. While the formal doctrine still called for the employment of complete battalions, the Tank Destroyer Center began to emphasize a new focus on combined arms training and small-unit actions. New field manuals were prepared to discuss the independent operation of tank-destroyer platoons, and crews began to have specialized training in their secondary roles, such as indirect gunnery or anti-fortification work.

Changes in training were made to ensure that tank destroyer units acted according to operating procedure. This was necessary because too many tank destroyer units in North Africa were "behaving like tanks"[18] and attacking German tanks "head-on", despite their lack of armor. Further training changes involved the role of the organic reconnaissance companies, which were not adequately performing their assigned tasks: route and area reconnaissance with the specific aim of finding locations for tank destroyers to ambush approaching enemy tanks.[19]

A M10 of the 701st TD Battalion advancing along a mountain road, in an example of the broken terrain common in Italy

The second theater of operations for tank destroyer units was the Italian campaign, beginning with the landings in Sicily in July 1943, and continuing into mainland Italy that September. While German armor was present in the theater, it was rarely committed to battle in large groups; this was partly a result of the broken, heavily cultivated, terrain, but also due to a growing conservatism and defensive ethos on the German side. As a result, the tank destroyers found themselves used for a variety of other tasks, most commonly local artillery support.

A report in late 1944, reviewing the use of tank destroyer units in combat, found that in practice they were often expected to fulfill the roles of armor support:

During the planning stage for an attack it was found that practically without exception the infantry commanders were reasonable in their requirements and expectations of support by the tank destroyers. But once the battle was joined, the original plans with few exceptions were often discarded and the destroyers were ordered to go forward as tanks ahead of the infantry...[21]

When operating with armored forces, it was common to attach a company or a platoon to a tank battalion or company, and use them in an overwatch role. When operating in defense, tanks and tank destroyers were pooled as a rear-area reserve and brought into the line to blunt tank-led attacks against infantry positions.

A major lesson learned from the Italian campaign was that the conversion to towed guns was not as advantageous as had been previously thought. The mobility and protection of the tank destroyer was found to outweigh the towed anti-tank gun's low profile. At Anzio, a number of British towed anti-tank gun units were overrun and knocked out simply because they were unable to redeploy on short notice, while self-propelled guns were able to fall back and continue fighting.

In Italy, the last few M3 GMC were replaced by the M10. Although the M10 was incapable of dealing with the frontal arc of the rarely-encountered Panther tanks and Tiger tanks, it was sufficient against most enemy armor encountered in Italy, and against heavy tanks from the flank. The M18 was first deployed in the summer of 1944, and was not seen as a great success in the Italian theater; its high speed was only of limited use in the restricted terrain, and as a result it was effectively a slightly up-gunned M10.

In August 1942, the Tank Destroyer Command was redesignated the "Tank Destroyer Center," representing a "sharp restriction of authority" to purely a training establishment, with tank destroyer battalions leaving the custody of the Center entirely after their training was finished. From a high of 220 battalions, now deemed excessive, the 1943 troop basis called for only 114. In April 1943, it was called for that only 106 battalions be activated, the number active or in the process of activation at that time. By October 1943, it was found that the need for tank destroyers overseas was far less than had been expected, and the Tank Destroyer Center began to reduce its training activities.

Thirty-five tank destroyer battalions never left the United States. Twenty-five battalions were broken up in 1943 and 1944 for their manpower, either to reinforce existing battalions, for assignment to special non-divisional infantry regiments for a six-week period of training to be converted to infantry replacements (the bulk of the battalions), or were kept occupied with miscellaneous tasks such as serving as school troops, until their inactivation. Ten battalions (not counting one that did so while overseas) were converted to other types of units, chiefly tank, amphibious tractor, or armored field artillery battalions.[4]

M10 tank destroyer in action near Saint-Lô, June 1944.

By far the largest employment of tank destroyer units was in the north-western Europe campaign through France, the Low Countries and Germany. They were employed from the very beginning of the campaign, with one battalion being landed on Utah Beach in a follow-up wave on D-Day.

A revised version of Field Manual 18–5, introduced in June 1944, broadened the doctrine of tank destroyer operations. It allowed for a more dispersed deployment of the battalions throughout a force, and recommended that when enemy armor was only expected to be deployed in small groups, tank destroyers were to be distributed among forward units. It became general practice to attach a tank destroyer battalion semi-permanently to a division; this meant that it was locally available for emergencies, and that it would be able to train alongside "its" division when out of the line.

The most significant employment of tank destroyers in Normandy was in early August, at the Battle of Mortain, where the 823rd Tank Destroyer Battalion (towed 3-inch guns) was on the defensive alongside the 30th Infantry Division. The division, which was in temporary positions and not prepared for a defensive engagement, was attacked by elements of four panzer divisions on 6 August, under heavy fog. The 823rd put up a strong defense—knocking out fourteen tanks—but took heavy losses, being mostly overrun and losing eleven guns. This served to reinforce misgivings about the effectiveness of the towed units, and a report delivered to the Pentagon in December recommended they be phased out in favor of self-propelled units.

It was in France that the allies first began to face the German Panther tank. The superior frontal armor of this tank, along with the Tiger I, Tiger II, and newer Panzerjägers, made the 75mm armed US tanks and tank destroyers less effective. The presence of these German tanks expedited the development and production of US armored vehicles armed with 90mm guns - the first to be introduced being the M36 tank destroyer.

In December 1944, and January 1945, the Battle of the Bulge put American ground forces on the operational defensive for the first time in Europe, as a German army group of 24 divisions (including ten panzer divisions with 1,500 armored vehicles) launched a major offensive in the Ardennes forest. The main thrust fell on the 99th and 2nd Infantry divisions which jammed the northern shoulder. A secondary attack hit two overstretched infantry divisions, both with attached towed tank destroyer battalions.[lower-alpha 8] Once contact was made, the towed guns were unable to reposition themselves or withdraw, and were often overrun by the enemy advance, or simply outflanked by infantry.[lower-alpha 9] The gun crews, unlike their self-propelled counterparts, had no protection against small-arms fire, and could easily be driven back by a squad of infantry. This lack of mobility was aggravated by the cold wet weather, and the rough conditions, which tended to bog down wheeled vehicles and immobilize fixed guns. Throughout the 1st Army as a whole, three-quarters of the tank destroyers lost were towed rather than self-propelled. One battalion, the 801st, lost 17 towed guns in just two days, while the M10-equipped 644th, which fought alongside it, found ideal opportunities for close-range ambushes and claimed 17 tanks in the same time period. It was clear that the towed guns had proved ineffective and, once the Ardennes offensive had been dealt with, the U.S. War Office approved Eisenhower's January 1945 request to convert all remaining towed units in the theatre to self-propelled guns.

Despite US forces being subjected to a major armored thrust by the Germans in the Ardennes, Tank Destroyer units were not ordered to engage the enemy according to stated doctrine. This was because most units had already been attached to Divisions and had been broken up into smaller infantry support units in a similar fashion to the way separate Tank Battalions had been. Moreover, the loss of lines of communications led to the smaller units being controlled by local commanders rather than being directed by Corps or Army commanders.

Northern Sector - Kampfgruppe Peiper Nevertheless, tank destroyers were to be found throughout the fighting in the Battle of the Bulge, fighting at close range in broken terrain much as they had done in Italy, and, despite their shortcomings, were an essential part of the successful defense. They were widely used during the Ardennes fighting, especially in the northern sector around Malmedy, Spa, Stoumont. Large numbers were involved in several actions against the tanks of Kampfgruppe Peiper, the spearhead of the German 6. Panzer Army, around La Gleize. Elements of the 740th Tank Battalion and 823rd Tank Destroyer Battalion closed from Remouchamps were deployed into defensive positions in front of Stoumont alongside elements of the 3rd Armored division, the 30th Infantry Division and the 82nd Airborne Division.[23]

The battle was also the first major engagement of the M36, with its 90 mm gun; the three battalions employed (the 610th, 703rd, and the 740th Tank Destroyer Battalions) proved highly effective. The M36 was beginning to be introduced in number when the offensive began, and was important throughout the entire Ardennes offensive.

Southern Sector - Bastogne The 705th, equipped with M18s, fought alongside the 101st Airborne at the siege of Bastogne, and played a key role in the defense of the town. Four M-18s, along with some M4 medium tanks and infantry from the 10th Armored division, occupied Noville, just north of Bastogne, and stopped a German armored attack with flank fires, killing 30 heavy tanks (Panthers and Tigers).[24] Once surrounded, the actions of mobile Tank Destroyers within Bastogne was similar to stated doctrine - whenever German attacks threatened the front lines, tank destroyer units (along with US tanks) would rush to the area from behind and intercept invading armor. Because of the shortness of the interior lines within the besieged Bastogne, Tank Destroyer units could be directed very quickly to any location in response to a German attack and prevented any breakthrough.[25]

The battle also highlighted the defensive nature of Tank Destroyer tactics compared to regular armored units. During Team Desobry's initial occupation of Noville, a number of US tanks and tank destroyers were firing into advancing units of the 2nd Panzer Division. However, so many targets were appearing that the M4 tanks from CCB of 10th Armored were staying in place and not moving. By contrast, the M18s from the 609th Tank Destroyer Battalion made frequent changes in location after firing. As a result, tank losses were high while Tank Destroyer losses were comparatively low.[26]

Central Sector - St. Vith The mobile defense of the Battle of St. Vith involved M36 tank Destroyers from the 814th Tank Destroyer Battalion blunting German armored thrusts. Once these thrusts were halted, tank companies from the 7th Armored Division would counter-attack. This tactic allowed a gradual retreat of US forces, ceding only a few kilometers a day, and was instrumental in ruining the plans of advancing German forces.

While the tank destroyers were broadly used in their intended role in the Ardennes—being used as a reserve to counter a massed armored attack – there were two significant differences between their use and the original doctrine. Firstly, there was no central strategic reserve—most tank destroyer battalions were assigned to divisions and kept near the front line, rather than massed in the rear. Secondly, the battalions were rarely committed as a whole; as had become common, they were effectively used as local anti-tank assets, with a platoon or a company assigned to an infantry battalion to bolster its defensive strength.

Soldiers of a tank destroyer battalion warm themselves with coffee before going into action against the Germans near Stolberg, Germany. 16 November 1944.

M36 of the 702nd Tank Destroyer Battalion engaged in indirect fire duty, 16 December 1944.

After losses in the Battle of the Bulge, German armored capability in the West was seriously weakened, both through combat losses and through logistical limitations. As such, the tank destroyer battalions spent the closing months of the war as mobile support units, broadly distributed into secondary roles.

As a result, mobile tank destroyer forces generally operated in the same way as the separate tank battalion - being used as direct fire support for infantry operations across a broad front. But while tanks were effective in this role, the tank destroyers were handicapped by their open turrets and thin armor, making them more vulnerable to enemy fire. Moreover, the speed advantage that some tank destroyers had over tanks did not translate into a tactical advantage since such support operations moved at the speed of foot infantry. Infantry units did, however, appreciate the support of tank destroyers in lieu of available tanks.

The remaining towed tank destroyer battalions were generally attached to infantry divisions in more static areas, offering limited direct fire support in the same way as the mobile battalions, or else being attached to divisional artillery to augment indirect fire missions.[27] Most of the towed battalions were gradually refitted with mobile units after the Ardennes and retrained.

By the war's end, infantry division commanders "unanimously agreed that they would prefer to have the support of a tank battalion instead of a tank destroyer battalion."[28] The result was a belief that each infantry division would have its own dedicated battalion of three tank companies, with each company serving each of the three Infantry Regiments. This made the Tank destroyer doctrine obsolete, since tanks themselves could also serve in the role of a mobile anti-tank defense against any potential enemy armored thrust, a tactic that had been proven during the Ardennes.

A small number of tank destroyer battalions served in the South-West Pacific; due to the lack of Japanese armor, these were employed almost entirely in the infantry support role, effectively acting as highly mobile artillery. Due to their open-topped turrets, the tank destroyers were far more vulnerable than tanks to close-assault tactics used by the Japanese infantry.

All the US tank destroyers were built without turret roofs. This was done to save weight but also allowed a wider field of view to spot enemy armor[16] and quicker ammunition stowage. The drawbacks included vulnerability to small arms fire (especially from elevated positions), grenades, and splinters from air bursting artillery.[32] Exposure to wind, rain, snow and freezing temperatures also made operations difficult, and many tank destroyer crews placed tarpaulins or other material over the turret to improve both their comfort and their operational effectiveness.[33] Other significant differences between tank destroyers and tanks was that tank destroyers lacked coaxial and bow .30-caliber machine guns. This reduced their ability for infantry support and close-in self defense. Tank destroyers did retain a turret top .50-caliber machine gun as did medium tanks and useful for reconnaissance by fire and self defense.