M5 Light Tank (USA)

Development
Combat
North Africa
Italy
Europe
Pacific
Variants
Stats (M5/ M5A1)

The M5 Light Tank was developed in an attempt to make sure that a shortage of the Continental engines used in the M3 Light Tank wouldn't disrupt production of light tanks. It was powered by two Cadillac car engines, and was produced alongside the later versions of the M3, replacing it in US Army service. 

Development

In July 1941 the Ordnance department was worried that the increase in aircraft production might cause a shortage of the Continental radial engine used in the M3 Light Tank. They began to hunt for alternative petrol engines, and General Motors suggested using a pair of Cadillac automobile engines combined with Hydro-matic transmission. A prototype, with the designation M3E2, was developed by the summer of 1942 and underwent tests at the Aberdeen Proving Ground. The new engine was a success - it provided more power, was smoother running, quieter and easier to drive. It also took up less space in the fighting compartment allowing the use of a better turret basket. The M3E2 had the same superstructure as the M3A1, but with a raised engine deck.

In October the M3E2 design was standardised as the Light Tank M4, but in November the project was merged with the M3A1E1, a design for an M3 with a homogenous welded hull. The prototype was modified and became the M3E3. This featured the new turret basket and photographs show it with the greatly modified superstructure used on the M5 (and later the M3A3). This version of the tank was standardised for production in February 1942, this time as the Light Tank M5. The M4 designation was abandoned in order to avoid confusion with the M4 Medium Tank (Sherman)

The designs of the M3 and M5 leapfrogged each other for the next two versions. The final version of the M3, the M3A3, combined the improved superstructure of the M5 with the Continental engine. It also gained a new turret with a bustle that contained the radio, better vision slots and an improved mount for the 37mm gun. The M3A3 wasn't used in combat by the Americans, but did see use with the British and other recipients of Lend-Lease.

The M3A3 was followed by the M5A1, which introduced all of the improvements made to the M3A3. Production of the M5A1 began in September 1942, alongside the M3A3.

The M5 used vertical volute spring suspension. There were four road wheels on each side of the tank, carried in pairs on two bogies. Each wheel was carried on a pivoting arm that was connected almost horizontally to a central mounting bracket. Shock absorption was provided by a vertical spring that connected the pivoting arm to the top of the bracket, protected from damage by the outer face of the bracket. On some tanks the return rollers were attached to the top of the suspension bogies, but that wasn't the case on the M5. The vertical volute system was simple to produce and maintain and if any part of a bogie was damaged the entire unit could easily be replaced. A similar system was used on most M4 Shermans. 

The M5 was produced at four factories. The original Cadillac production at Detroit was joined by the Cadillac factory at Southgate, California and Massey-Harris at Racine, Wisconsin, both in July 1943. Finally American Car & Foundry moved from the M3A3 to the M5A1 in October 1943. Production of the M5 ended in June 1944.

Combat

North Africa

The M5 equipped the light tank battalions of the 2nd Armored Division during Operation Torch, and was used during the landings at Casablanca in November 1942. The division saw little fighting at Casablanca, although the 70th and 756th Independent Tank Battalions were involved with some clashes with the French.

Its M5s didn't see much combat in Tunisia. During the fighting in North Africa the M5 was slowly replaced by the M5A1, although some of the older tanks remained in use to the end of the war.

By the spring of 1943 the commanders of the light tank battalions wanted both the M3 and M5 declared surplus and withdrawn from combat, but this was never really likely to happen. The T7 Light Tank, which was meant to enter service as the M7 and replace the earlier vehicles, kept being up-gunned until it was virtually a medium tank, and the project was cancelled. The M3 was withdrawn in the European theatre, but it was replaced by the M5.

Bradley and Patton felt that the M5 could still be used for reconnaissance and flank security. A new table of organization and equipment for tank battalions was issued on 15 September 1943. In this system there would be three medium tank companies, each with 17 M4 Shermans and one M4 Sherman (105mm) and one light tank company with 17 M5A1 light tanks. These would act as scouts and provide flank protection while the Shermans performed the main combat role.

Italy

The M5A1 was the main US light tank during the invasion of Sicily and during the Italian campaign. A number of M5s were also used. By this point the tank battalions had been reorganised, so the light tanks were no longer expected to operate alone. They saw combat throughout the Italian campaign, from the early landings in the south to the advance on Rome in the summer of 1944 and the final battles in the north.

Europe

The M5A1 was the main American light tank in use by D-Day. A number of M5s also saw combat in France and Germany, normally as replacements when the supply of M5A1s ran short.

Most light tanks were found in the light tank companies of the restructured tank battalions, although two battalions that served in the ETO were still organised as light tank battalions and were almost entirely equipped with the M5A1.

The M5A1 was now seen as very vulnerable against modern German tanks, and was also unable to damage most German tanks even at point blank range. It was no longer used to attack German armour, and instead became an infantry support weapon, used to support mechanized infantry companies. This vulnerability was recognised on D-Day, and very few M5A1s landed until the beaches had been secured.  

Despite these new tactics the losses of M5A1s were so high that Bradley's 12th Army Group requested that the M5A1 be withdrawn and replaced with the M24. Not only were losses high, but light tank crews also suffered high casualty rates - 1 in 3 were killed when a light tank was penetrated, while for the medium tank the ratio was 1 in 5.

The Army turned downs Bradley's request. There were already over 1,000 M5A1 light tanks in US army service in France, and the M24 wouldn't be available in large numbers until the end of 1944. Casualty rates for the M5A1 did fall from September, but this was mainly because tank commanders were increasingly careful with them,

The M24 started to appear in larger numbers in December 1944, although only the 7th Armoured Division fully converted to the new type. There were thus plenty of M5A1s in service during the Battle of the Bulge. On 18 December 1944 Tank Force Harper, from the 9th Armoured Division, was overrun between Bastogne and St. Vith. Some of its tanks were captured and were later used by 2.Panzer Division as static defensive weapons. The M5A1 was also involved in the crucial battle for Bastogne, with some inside the town and others involved in the 4th Armoured Division's successful attempt to lift the siege.

Non-combat roles became increasingly common late in the war. Over the winter of 1944-45 they were used to evacuate wounded tankers from medium tank companies from areas where wheeled ambulances would have been unable to operate. They were also given loudspeakers and used for psychological warfare, especially in attempts to get German towns to surrender without resistance.

Several things were done to try and reduce the risk from panzerfausts and other anti-tank weapons. Some tanks carried sandbags while photos show others with thick planks attached to the side of the vehicle.

Pacific

The M5 remained in use as a main battle tank for much longer in the Pacific than in other theatres. It was better than the Type 95 Ha-go light tank. The Type 97 Chi-ha medium tank had a more powerful 47mm gun, but much thinner armour (only 25mm at its thickest), so the M5 and M5A1 could fight it on at least equal terms. The Japanese also lacked good anti-tank guns until the last year of the war, so one of their main anti-tank techniques was to use infantry to try and swarm over the American tanks and destroy them with satchel charges. As a result American tanks often operated in pairs, each using its machine guns to keep the other free of Japanese infantry.

Late in 1943 the US Marine Corps tank battalions began to get medium tanks, following the same format as the US army with three medium tank companies to one light tank company. The M5A1 entered marine service at this point.

The M5A1 was first used in combat in the Pacific in December 1943 when the Marine 1st Tank Battalion used them during the landings at Cape Gloucester.

The Marine 4th Battalion used the M5A1 during the invasion of Kwajelein Atoll in the Marshall Islands in February 1944. They were used on Namur at the northern side of the Atoll

The M5A1 was used by both the Army and the Marines during the invasion of Saipan in the summer of 1944. The Army's 762nd Tank Battalion used it uring the initial landings and was credited with the most tank kills in battles with the Japanese 9th Tank Regiment.

The Marine 4th Battalion also used the M5A1 on Saipan. They had used the M3A1 Light Tank on Tarawa in 1943, where the 37mm main gun had been found inadequate to deal with Japanese bunkers. On Saipan the M3 was normally equipped with the Satan flamethrower, while the M5A1 was used as a gun tank to guard the flamethrower tanks.

In the last year of the war the Japanese finally got a large number of 47mm anti-tank guns, which were able to penetrate the armour of the M5. As a result the Americans shifted towards the M4 Sherman, but there were still some M5A1s in use during the fighting on Leyte in the autumn of 1944, where they were serving with the 44th Tank Battalion. They also took part in the landings at Lingayen Gulf on Luzon in January 1945. 

Variants

M5

The M5 was the initial production version, with an all-welded hull and the modified M3A1 turret without a cupola.

M5A1

The M5A1 was the second production version, with the improvements introduced in the M3A4, including a turret bustle to carry a radio.

M5 Command Tank

A version with the turret removed and a box-like superstructure added. Armed with a .50in Browning machine gun on a flexible mount

M5A1 with Psy-war equipment

This version was given a loud hailer and was used by the Psychological Warfare units during 1944-45, in particular in attempts to convince German towns to surrender without resistance.

M5A1 with E7-7 Flame-gun

The E7-7 Flame-gun replaced the main 37mm gun. The fuel was stored in the hull, limiting the amount that could be carried.

M5A1 with E9-9 Flame-gun

One prototype of the M5A1 with E9-9 flame-gun was produced. This was based on the British Crocodile, which involved carrying the fuel in a separate towed trailer, linked to the tank by an armoured pipe. This increased the amount of fuel that could be carried and also reduced the chances of a disastrous fuel explosion.
 
M5A1 with E8 Flame-gun

The M5A1 with E8 Flame-gun was the most dramatic flame-thrower modification. An entirely new superstructure was installed, with the flame-gun carried in a small rotating turret. One prototype was built.

M5 with T39 Rocket Launcher.

The T39 Rocket Launcher carried twenty 7.2in rockets in two rows. It was installed on top of the turret and was controlled by moving the main gun. This didn't progress beyond the prototype stage.

M5A1E1

The M5A1E1 had wider tracks and an automatic 37mm gun. It reached trials status but was abandoned in 1943 as work progressed on the far superior M24 Chafee.

M8 Howitzer Motor Carriage

The M5A1 was the basis of the successful M8 Howitzer Motor Carriage, which carried a 75mm howitzer in an open topped turret and was used to provide fire support for M5 companies.

T27 81mm Mortar Motor Carriage

The T27 was an attempt to mount an 81mm mortar in the superstructure of a M5 with the turret removed. Two designs were produced but the project was cancelled in April 1944.

T29 4.2in Mortar Motor Carriage

The T29 was a modified version of the T27 produced in an attempt to improve the use of space. As with the T27 it was found to be too cramped and was cancelled.

T8 Reconnaissance Vehicle

The T8 Reconnaissance Vehicle was a conversion of the M5. The turret was removed and a .50in machine gun mounted on an open position. The T8 was accepted as a limited standard vehicle and saw some combat.

Stats (M5/ M5A1)
Production: 2,074/ 6,810; total 8,884
Hull Length: 14ft 2 3/4in/ 15ft 10 1/2in
Hull Width: 7ft 4 1/4in
Height: 7ft 6 1/2in
Crew: 4 (commander, gunner, driver, co-driver)
Weight: 33,000lb/ 33,907lb
Engine: 220hp Cadillac Twin V8
Max Speed: 36mph road, 24mph cross-country
Max Range: 100 miles road range
Armament: One 37mm gun and one .30in machine gun in turret, one .30in machine gun in hull, one AA machine gun on turret roof
Armour: 12-67mm

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How to cite this article: Rickard, J (21 February 2014), M5 Light Tank (USA) , http://www.historyofwar.org/articles/weapons_light_tank_M5.html

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