The M3 half-track is an American armored personnel carrier half-track widely used by the Allies during World War II and in the Cold War. Derived from the M2 half-track car, the M3 was extensively produced, with about 15,000 standard M3s and more than 38,000 variant units manufactured.
The M3 was extensively modified with several dozen variant designs produced for different purposes. During World War II, the M3 and its variants were supplied to the U.S. Army and Marines, as well as British Commonwealth and Soviet Red Army forces, serving on all major fronts throughout the war. The M3 and its variants were produced by many manufacturers including Diamond T, White Motor Company, and Autocar. They were adapted for a wide variety of uses, such as a self-propelled anti-aircraft weapon or self-propelled artillery. Although initially unpopular due to its lack of significant armor or a roof to protect the passengers and crew from shrapnel, it was used by most of the Allies during the war.
In the Cold War era, the vehicle was used by a variety of state and non-state operators in conflicts in South America, the Middle East, Africa, and Asia, remaining in service until as late as the mid-1990s.
Specifications The M3 half-track was long, wide, high and had a gross weight of either (M3) or (M3A1). The wheelbase was long. The suspension consists of a leaf spring for the two front wheels, while the rear treads had vertical volute springs. With a fuel capacity of 60 US gallons (230 L), the M3 could carry its crew (one driver) and a squad of 12 soldiers before refueling, while protecting them from small arms with light armor (6–12 mm of armor). The vehicle was powered by a White 160AX, 386 in3 (6,330 cc), 6-cylinder gasoline engine.*
Design The design, which used many commercial components to improve reliability and the rate of production, was standardized in 1940 and built by the Autocar Company, Diamond T Motor Company, and the White Motor Company. With a White 160AX engine, the M3 was driven through a manual constant-mesh (non-synchromesh) transmission with four forward and one reverse gear, as well as a two-speed transfer case. Braking was hydraulic assisted while steering was manual. Onboard electronics run on a 12-volt system.Berndt (1993), p. 152. The vehicle uses two tracks made of molded rubber over steel cabling with metal track guides.Mesko (1996), p. 8.
Infantry rifles were held in brackets behind the seats while ammunition and rations were generally stored underneath. In 1942, the vehicles were fitted with small racks for land mines on the outside of the hull, just above the tracks. In combat, many squads found it necessary to stow additional rations, rucksacks and other crew stowage on the outside of the vehicle. Luggage racks were often added in the field, and later vehicles were fitted with rear-mounted racks for this purpose.Zaloga (1994), p. 11
Early vehicles had a pintle mount just behind the front seats that mounted a .50-caliber (12.7 mm) M2 Browning machine gun. The later M3A1 adopted a raised, armored "pulpit" mount for the .50-caliber machine gun over the front passenger seat, and additional mounts for .30-caliber (7.62 mm) machine guns along the sides of the passenger compartment. Many M3s were later converted to M3A1s. The vehicle body was fully armored, with an adjustable armored shutter for the engine radiator, and adjustable bulletproof panels with vision slits for the windshield, driver windows, and passenger windows.Zaloga (1994), pp. 6–7
Development
The development of an armored half-track began with ordnance directive OCM 14188 to convert an M3 Scout Car into a half-track. The prototype was built at Rock Island Arsenal with help from White Motor Company and was designated the T7. It had the same chassis and engine as the M3, but had larger front wheels and a shorter front clip. The armor consisted of 1/4-inch thick hardened armor plate, and it was armed with two M1919 machine guns and one M2 Browning machine gun operated by a crew of eight. Tests at Aberdeen Proving Ground in 1938 demonstrated unsatisfactory performance due to the front-wheel drive. The T7 was converted back into a scout car and returned to the Army.Hunnicutt (2001), p. 25.
Throughout 1939 and 1940, the M2 half-track car was prototyped and developed by the Army at Aberdeen Proving Grounds. The M3 was developed as a larger version of the M2 equipped with two M1919 machine guns and an M2 Browning machine gun for combat usage. The M3 also added a rear door and five additional seats in the rear. The M3 was tested at Aberdeen Proving Grounds in the summer of 1941 and was accepted into service soon after.Hunnicutt (2001), p. 33.
Service history
In US service, it was intended that the M3 would be issued to armored infantry regiments. It was also quickly put into action with the Provisional Tank Group when the Japanese Army began their invasion of the Philippines. At first, there were multiple complaints due to several mechanical difficulties. These were rectified by the Ordnance Department after receiving field reports from the Philippines. The M3s first use in its intended role was during Operation Torch. Each armored division had 433 M2s or M3s, 200 in the armored regiments and 233 in the armored infantry regiment.
The half-tracks were initially unpopular and nicknamed "Purple Heart boxes" (a grim reference to the US Army decoration for combat wounds) by American troops. The chief complaints centered on the complete lack of overhead protection from artillery shells bursting overhead and that the armor was inadequate against machine gun fire. Omar Bradley quoted in his report about half-tracks that it was "a competent and dependable contrivance. Its bad name resulted from the inexperience of our troops who attempted to use it for too many things".Zaloga (1994), p. 8. Another major issue with the M3 was its fixed rear idler, which often broke on rough terrain. Commanders in North Africa bought parts to build spring-loaded rear idlers that could handle the rough terrain, which the Ordnance Department then approved as an official fix.Zaloga (1994), p. 11.Hunnicutt (2001), p. 40. In 1943, the M3 served in Sicily and Italy and received positive reports of it in action. It operated in Operation Overlord and served in Europe for the remainder of the war.Zaloga (1994), pp. 15–16.
The vehicle was generally considered very mechanically reliable, although there were two major complaints: the vehicle had a wide turning radius and lacked power steering, the latter especially evident when using narrow European streets. The unique design of the track, made up of steel bands with a rubber contact surface vulcanized to them, made replacement difficult; if the track became damaged or the steel bands stretched out, the entire track had to be replaced. A track with replaceable blocks was suggested as an alternative.
Total production of the M3 and its variants ran to nearly 54,000 vehicles.Zaloga (1994), p. 42 To supply the Allied nations, International Harvester produced several thousand of a very similar vehicle, the M5 half-track, for Lend-Lease.Zaloga (1994), p. 12.
Variants
Armored personnel carriers
M3 – White and Autocar half-track with White 160AX engine. Fitted with either an M32 anti-aircraft machine gun mount or a pedestal mount, both featuring an M2HB machine gun. M3A1 – A M3 with the improved M49 machine gun ring mount over the right hand front seat. Between 1942 and 1943 all M3 half-tracks (standard and A1s) were continually upgraded. These improvements included a number of drive train, engine, and stowage improvements. T29/M3A2 – Developed in 1943 to combine features such that existing M2 and M3 production could be switched to a common vehicle. The need for additional half-tracks was not as large as predicted, and the M3A2 was never built. M3E2/M5 half-track – International Harvester half-track, externally largely identical to the M3, but with , IHC RED-450-B engine, different drive train and fuel and electrical system. The chassis, bogies, track, idler and drive sprockets, wheels, winches, transfer case, rollers, and machine gun mount are interchangeable with the M3. The M5 was heavier than the M3, due in part to heavier armor. The body of the vehicle was welded, rather than bolted. The M5 was primarily built for Lend-Lease to the European allies.Berndt (1993), p. 147. M5A1 – Similar to the M3A1, the M5A1 was an M5 with the M49 machine gun mount. It could fit one .50-caliber (12.7 mm) and two .30-caliber (30.06) machine guns. The IHC models had a slightly lower top speed (only ) and lower range (). T31/M5A2 – Similar in principle to the M3A2, the M5A2 was a vehicle developed by the US Ordnance Department to combine the production of the M5 and M9 into a single vehicle. As with the M3A2, the project was never needed, and was never produced.Hunnicutt (2001), p. 52. M9 half-track – Same body as the M5, but with stowage arranged as in the M2 half-track car, access to radios from inside (as opposed to outside) and rear doors, plus an pedestal MG mount. M9A1 – Same as M9, with ring mount and three MG pintles.
Self-propelled guns
T12/M3 75 mm GMC – M3 based gun motor carriage equipped with the M1897A5 75 mm gun. Also fitted with the M2A3 gun carriage and shield.Hunnicutt (2001), p. 98. M3A1 75 mm GMC – The M2A2 gun carriage was substituted for the A3, as stocks of the former were exhausted. Later variants featured a purpose-built gun shield (59 rounds). T19 105 mm HMC – M3 based howitzer motor carriage equipped with the M2A1 105 mm howitzer (8 rounds). T19/M21 81 mm MMC – M3-based mortar motor carriage equipped with the M1 mortar (81 mm) (97 rounds), designed to allow the mortar to be fired from within the vehicle.Hunnicutt (2001), p. 112. T21 – M3 based mortar carrier fitted with a 4.2 inch mortar. Never adopted.Hunnicutt (2001), p. 96. T21E1 – The T21's mortar could only fire rearward as with the M2 based M4 MMC. The T21E1 reoriented to the mortar to fire forward. T30 75 mm HMC – M3 based howitzer motor carriage equipped with the M1A1 75 mm howitzer in a simple box mount (60 rounds). Used by the US Army. Also provided to the Free French Army, later used in Indochina.Zaloga (1994), pp. 36–37 T38 105 mm HMC – M3 based howitzer motor carriage equipped with the M3 105 mm howitzer. Cancelled with the success of the T19 105 mm HMC.Hunnicutt (2001), p. 121. T48 gun motor carriage – M3 based gun motor carriage equipped with the M1 57 mm gun, an American copy of the British QF 6 pounder anti-tank gun. A total of 962 T48s were produced during the war. Of these, 60 were supplied under lend lease to Britain, and 650 to the USSR who designated it SU-57 (99 rounds). A total of 31 were converted into M3A1s, while one entered service with the U.S. Army.Zaloga (1994), pp. 35–36Mesko (1996), p. 22.
Anti-aircraft variants T1E4/M13 half-track – M3 based multiple gun motor carriage equipped with the Maxson M33 mount with two M2HB machine guns (5,000 rounds). The T1E4 prototypes had the hull sides removed for ease of working with the mount. These were reintroduced on production M13s. This was a development of previous T1s that had all been based on the M2 half-track car. M14 half-track – M13 MGMC variant, based on the M5 chassis. Supplied under lend-lease to Britain (5,000 rounds).Zaloga (1994), p. 38.
M16 half-track – M3 based multiple gun motor carriage equipped with the Maxson M45 Quadmount (specifically the M45D) with four M2HB machine guns (5,000 rounds).Hunnicutt (2001), pp. 123–126 M16A1 MGMC – Standard M3 personnel carriers converted to multiple gun motor carriages by removing rear seats and installing a Maxson M45 mount (more specifically the M45F, which featured folding "bat wing" gun shields on both sides of the mount over the machine guns). These vehicles are easily identified by the lack of the folding armored hull panels found on purpose-built M16s.