M3 Lee
The M3 Lee, officially Medium Tank, M3, was an American medium tank used during World War II. The turret was produced in two different forms, one for US needs and one modified to British requirements to place the radio next to the commander. In British Commonwealth service, the tank was called by two names: tanks employing US-pattern turrets were called "Lee", named after Confederate general Robert E. Lee, while those with British-pattern turrets were known as "Grant", named after Union general Ulysses S. Grant.
Design commenced in July 1940, and the first M3s were operational in late 1941. The US Army needed a medium tank armed with a 75 mm gun and coupled with the United Kingdom's immediate demand for 3,650 medium tanks, the Lee began production by late 1940. The design was a compromise meant to produce a tank as soon as possible and serve only until replaced by the following M4 Sherman tank. The M3 was reliable, had considerable firepower, good armor, and high mobility but had serious drawbacks in its general design and shape, including a high silhouette, an archaic sponson mounting of the main gun preventing the tank from taking a hull-down position, and riveted construction.
It was considered by Hans von Luck, to be superior in May 1942 to the Panzer IV and able to operate out of range of German 5 cm anti-tank guns. However, by mid-1943, with the introduction of upgunned Panzer IIIs and Panzer IVs, the tank had been withdrawn from combat in most theaters and replaced by the more capable M4 Sherman tank as soon as it became available in larger numbers.
Despite its being replaced elsewhere, the British continued to use M3s in combat against the Japanese in southeast Asia until 1945. Nearly a thousand M3s were supplied to the Soviet military under Lend-Lease between 1941 and 1943.
Development
The U.S. funded tank development poorly during the interwar years, and had little experience in design as well as poor doctrine to guide design efforts. Only a few tanks were built. A new medium tank was designed in 1938, tested as the T5 and accepted as the M2 Medium. The M2 used a radial engine and vertical volute suspension among many of the features of the M2 light tank.In, the U.S. Army possessed approximately 400 tanks, mostly M2 light tanks, with 18 of the M2 Mediums as the only ones considered "modern."
The M2 Medium Tank was typical of armored fighting vehicles many nations produced in 1939. By the time, the U.S. entered the war in 1941, the M2 design was already obsolete with a 37 mm gun, an impractical number of secondary machine guns, a very high silhouette, and frontal armor.
At the end June 1940 the National Munitions Program was introduced to address the United States lack of readiness in case of war across all branches of the armed forces. The program specified the building of over 1,700 medium tanks by the end of 1941. In mid July, Armored Force under Brigadier General Adna R. Chaffee Jr. was formed to take over responsibility for tanks which had previously been split between the Infantry and Cavalry commands. Work was begun with industry to create the production facilities leading to a contract in August for Chrysler to build the Detroit Tank Arsenal which was expected to turn out 10 Medium M2A1 per day.
However, the US Army's assessment of the German Panzer III and Panzer IV medium tanks' success in the French campaign was that a 75mm gun was a necessity. The M2A1 could not be fitted with a 75mm weapon in its turret. Producing a new turret design would delay production and while it was decided to start work on a 75mm turret design, an interim solution was sought. An experimental modification of an improved M2 Medium into a self-propelled gun - the T5E2 - had been tested with a 75m pack howitzer in the front hull and it was decided to base the interim design on this work. The existing M2 hull could be used with a redesigned superstructure and the M2A1 37 mm turret. The contract for 1,000 M2A1s was cancelled and replaced with one for 1,000 M3s, though the M3 had not yet been designed. The Ordnance Department allocated 60 days for the design work. At the same time, the 75 mm gun design was started by Watervliet Arsenal; the new gun was based on the 75mm field gun.
The design was unusual because the main weapon – a larger caliber, medium-velocity 75 mm gun – was in an offset sponson mounted in the hull with limited traverse. The sponson mount was necessary because, at the time, American tank plants did not have the design experience necessary to make a gun turret capable of holding a 75 mm weapon. A small turret with a lighter, high-velocity 37 mm gun sat on top of the tall hull. A small cupola on top of the turret held a machine gun. The use of two main guns was a feature of the French Char B1 and the Mark I version of the British Churchill tank. In the French tank, it had been designed as a self-propelled gun to attack fortifications and an anti-tank capability had been added through a second gun in a small turret; the Churchill carried a gun in the front hull to fire chiefly smoke shells. The M3 differed slightly from this pattern, having a dual-purpose main gun that could fire an armor-piercing projectile at a velocity high enough for effectively piercing armor, as well as deliver a high-explosive shell that was large enough to be effective. Using a hull-mounted gun, the M3 design could be produced faster than a tank with the same gun in a turret. It was understood that the M3 design was flawed, but Britain urgently needed tanks. A drawback of the sponson mount was that the M3 could not take a hull-down position and use its 75 mm gun at the same time.
The M3 was tall and roomy: the power transmission ran through the crew compartment under the turret basket to the gearbox driving the front sprockets. It was originally developed at the Rock Island Arsenal for T5 Phase III in 1938 but in 1940 Spicer Manufacturing Company was contracted to refine the design before serial production. Since Spicer itself was busy producing transmissions for the light tanks, Mack Manufacturing from 1940, and Iowa Transmission Co. from 1941 were tasked with manufacturing it. Steering was by differential braking, with a turning circle of. After some experiments with hydraulically powered steering on the earliest M3s mechanical long-lever operation was adopted for production.
The vertical volute spring suspension units possessed a return roller mounted directly atop the main housing of each of the six suspension units, designed as self-contained and readily replaced modular units bolted to the hull sides. The turret was power-traversed by an electro-hydraulic system in the form of an electric motor providing the pressure for the hydraulic motor. This fully rotated the turret in 15 seconds. Control was from a spade grip on the gun. The same motor provided pressure for the gun stabilizing system.
The 75 mm gun was operated by a gunner and a loader; sighting the gun used an M1 periscope – with an integral telescope – on the top of the sponson. The periscope rotated with the gun. The sight was marked from zero to, with vertical markings to aid deflection shooting at a moving target. The gunner laid the gun on target through geared handwheels for traverse and elevation. The shorter barreled 75 mm M2 cannon sometimes had a counterweight added at the end of the barrel to balance the gun for operation with the gyrostabilizer until the longer 75 mm M3 variant was brought into use.
The 37 mm gun was aimed through the M2 periscope, mounted in the mantlet to the side of the gun. It also sighted the coaxial machine gun. Two range scales were provided: 0– for the 37 mm and 0– for the machine gun.
File:M-3Grants-E 014053.2.jpg|thumb|British Grant and Lee at El Alamein 1942, showing differences between the British turret and the original design of the M3
There were also two.30-06 Browning M1919A4 machine guns mounted in the hull, fixed in traverse but adjustable in elevation, which were controlled by the driver. These were, due to coordination issues, removed, though they would be seen on early Sherman tanks.
Though not at war, the U.S. was willing to produce, sell and ship munitions including armored vehicles to Britain. The British had requested that their Matilda II infantry tank and Crusader cruiser tank designs be made by American factories, but this request was refused. With much of their equipment left in France after the British Army was evacuated from Dunkirk, the equipment needs of the British were acute. Though not entirely satisfied with the design, they ordered the M3 in large numbers. British experts had viewed the mock-up in 1940 and identified features that they considered flaws – the high profile, the hull mounted main gun, the radio position in the hull rather than in the turret, the riveted armor plating, the smooth track design, insufficient armor and lack of splash-proofing of the joints.
The British desired modifications for the tank they were purchasing. A bustle rack was to be made at the back of the turret to house the Wireless Set No. 19. The turret was to be given thicker armor than in the original U.S. design, and the machine gun cupola was to be replaced with a simple hatch. Extended space within the turret of the new M3 also allowed the use of a smoke bomb launcher, although the addition of the radio would take the space for storage of fifty 37 mm rounds, reducing the ammunition capacity for that gun to 128 rounds. Several of these new "Grant" tanks would also be equipped with sand shields for action in North Africa, though they often fell off. With these modifications accepted, the British ordered 2,000 Grants, with 1,685 ultimately built.
Contracts were arranged with four US companies for 500 tanks each: Baldwin Locomotive Company, Pullman Standard Car Company, Pressed Steel Car Company and Lima Locomotive Company. The total cost of the orders was approximately US$240 million, including funds for factory re-tooling. That was the total of all UK government funds held in the US; it took the US Lend-Lease act to solve the financial shortfall and fund future equipment orders. The order with Baldwin was later increased from 500 to 685. Lima did not produce a single Grant against its contract as it took the company so long to complete the steam locomotives already in production to create factory space and to tool-up that M3 production was winding down before it was ready. It was therefore agreed that Lima would supply 500 of the new M4 Sherman instead. Lima actually undertook the T6/M4 development while it was unable to manufacture the Grant and, as the other companies were all too busy, was the first company to begin producing the M4 in March 1942 with the M4A1 variant. The first 28 M4A1s built were British contract tanks as Grant replacements but the remainder of the order was subsumed into Lend-Lease.
The prototype M3 was completed in March 1941 and production models followed, with the first British-specification tanks produced in July. Both U.S. and British tanks had thicker armor than first planned. The British design required one fewer crew member than the US version due to the radio in the turret. The U.S. eventually eliminated the full-time radio operator, assigning the task to the driver. After extensive losses in Africa and Greece, the British realized that to meet their needs for tanks, they would have to take both the Lee and the Grant types.
The U.S. military used the "M" letter to designate nearly all of its equipment. When the British Army received its new M3 medium tanks from the US, confusion immediately set in between the different M3 medium tank and M3 light tank. The British Army was in the process of using names for its own tanks instead of designations and named its American tanks after American military figures, although the U.S. Army never used those terms until after the war. M3 tanks with the cast turret and radio setup received the name "General Grant", while the original M3s were called "General Lee", or more usually just "Grant" and "Lee".
The chassis and running gear of the M3 design was adapted by the Canadians for their Ram tank. The hull of the M3 was also used for self-propelled artillery as with the original design of the M7 Priest, of which nearly 3,500 were built, and recovery vehicles.