The Light Tank M24 entered US service towards the end of World War II. Intended to replace the M5 Stuart, the first thirty-four M24s reached Europe in November 1944, and were issued to the 2nd Cavalry Group in France. Although commonly referred to as `Chaffee’, this name was actually given to British Army M24s in recognition of General Adna R. Chaffee Jnr., who helped develop the use of tanks in the US armed forces. In all 4,731 M24s were produced.
Post-1945, the M24 saw action in the Korean War. As with other successful designs, it was sold to many armies around the world, and was used in local conflicts long after being replaced in the US Army by the M41 Walker Bulldog. By far the largest buyer of the M24 was France, with 1,260 units being procured via the `US Defense Military Aid Program’. Many of these saw action in the Algerian War, and later in the First Indochina War. While conditions in this latter conflict were not particularly suited to tank operations, the M24 benefitted from minimal ground pressure, allowing it to cope with the soft terrain.
Observations of the British experiences in the Western Desert fighting in 1942 when the 8th Army was using M3 series light tanks, showed that a heavier weapon was desirable for future US light tanks. A 75mm gun was fitted experimentally to a M8 HMC in place of the howitzer, and firing trials proved that it would be possible to develop a version of the M5 series light tank armed with the 75mm gun. Stowage space was severely restricted in the M5, however, more so with the fitting of a 75mm gun, and in addition the overall design of this vehicle was now dated and the armour thickness was inadequate. In April 1943, therefore, following the demise of T7 light/M7 medium programme (qv) the Ordnance Department, in conjunction with Cadillac (makers of the M5 series), began work on an entirely new light tank design which was to incorporate the best combinations of features from earlier designs with all lessons learned from previous experience. The twin Cadillac engines and Hydra-matic transmission which had been so successful and trouble-free in the M5 series were retained and the good accessibility which had been a feature of the T7 layout was adopted. A weight of 18 (short) tons was envisaged with an armour basis of only 25mm to save weight, but with all hull faces angled for optimum protection. Maximum turret armour was 37mm. Vertical volute suspension was replaced by road wheels on torsion arms to give a smoother ride. First of two pilot models, designated T24, was delivered in October 1943 and proved so successful that the Ordnance Department immediately authorised a production order for 1,000 vehicles which was later raised to 5,000. Cadillac and Massey-Harris undertook production, commencing March 1944 and these two plants between them produced 4,415 vehicles (including SP variants) by the war’s end. In each case production supplanted M5 series vehicles.
The 75mm M6 gun was adapted from the heavy aircraft cannon used in the Mitchell bomber, and had a concentric recoil system which saved valuable turret space. The T24 was standardised as the Light Tank M24 in May 1944. First deliveries of M24s were made to American tank battalions in late 1944, supplanting M5s, and the M24 came into increasing use in the closing months of the war, remaining as standard American light tank for many years afterwards.
Parallel to the need for a new light tank was the desire to produce a standard chassis as the basis of the so-called “Light Combat Team”-a complete series of tanks, SP guns, and special purpose tanks all based on one chassis so greatly simplifying maintenance and production. The many variants produced to meet this concept are given below. Each had identical engine, power train, and suspension to the M24.
M19 Gun Motor Carriage: Produced for the AA Command, this vehicle was originally designated T65E1 and built as a development of the T65 GMC (qv) with a twin 40mm M2 AA mount set at the hull rear and the engines moved forward to the hull centre. Design (by the Ordnance Department) commenced in mid-1943 and 904 vehicles were ordered in August 1944 when the design was standardised as the M19. By the war’s end, however, only 285 had been completed. M19s were standard US Army equipment for many years post-war. Crew: 6; weight 38,500Ib; height 9ft 9 1/2-in; elevation – 5° to + 85°; stowage 336 rounds, 40mm.
M41 Howitzer Motor Carriage: Prototype for this vehicle was the T64E1, a development of the T64 HMC (qv) which had been based on M5Al light tank components. The T64E1, however, featured the components of the “Light Combat Team” and was similar in layout to the M19, with centrally-mounted engines and the gun, a 155mm M1 howitzer, at the rear firing forward. It had a manually operated recoil spade and a folding crew platform. Unofficial name for this vehicle was “Gorilla”. Standardised as the M41 HMC, in May 1945,250 of these vehicles were ordered but only 60 were completed by the war’s end. The M41 HMC was standard US Army equipment for many years post-war. Details as for M24 except: Crew: 12 (8 carried in accompanying ammunition carrier); weight: 42,500Ib; length: 19ft 2in; trench crossing: 9ft; stowage: 22 rounds; range: 96 miles; elevation: +45° to – 5°; traverse: 17° left to 20° right; speed: 30mph.
M37 Howitzer Motor Carriage: Intended to supplement or replace the M7 HMC (qv) a new design based on the M24 chassis was produced, resembling the M7 in general layout. Designated T76 it was standardised in November 1944 as the M37 HMC with 105mm M4 howitzer. It had the same hull arrangement (ie, rear engine) as the M24 and compared with the M7 it had greatly increased ammunition stowage and improved armour protection. American Car & Foundry were given the production contract for 448 vehicles, but only 316 were completed, most of them after the war had ended when Cadillac took over the contract. Details as for M24 except: Crew: 7; weight: 40,000Ib; length: 18ft 2in; traverse: 22 to right and left; elevation: +45° to -10°; stowage: 90 rounds.
T38 Mortar Motor Carriage: This was a project to use the M37 HMC in the mortar carrying role. The 105mm howitzer was removed and the embrasure plated over. A 4·2in mortar was carried and fired from the fighting compartment. The project was cancelled in August 1945 when it became apparent that the war would end before the vehicle could go into service. A pilot model was completed.
T77E1 Multiple Gun Motor Carriage: This was a proposed AA tank development initiated in 1943 to mount a specially designed quad .50 cal machine gun turret on the M24 chassis. The turret was developed by the USAAF and featured remote control for the guns. Pilot vehicle, designated T77, was completed and tested at APG in July 1945. As a result of trials a computing sight system was added to the turret and the vehicle was re-designated T77E1. With the cessation of hostilities in September 1945, the project was abandoned.
M24 with swimming device: This was tested in the fall of 1944 and consisted of pontoons attached fore-and-aft to give flotation with grousers added to the tracks to give propulsion in the water, the idea being to allow the standard M24 to “swim” ashore from landing craft. Once ashore, the pontoons were jettisoned. This device was not used operationally. Designation for the device was M20.