In 1939, the U.S. Army possessed approximately 400 tanks, mostly M2 Light Tanks, with 18 of the to-be-discontinued M2 Medium Tanks as the only ones considered "modern". 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.
The M2 Medium Tank was typical of armored fighting vehicles (AFVs) many nations produced in 1939. When the U.S. entered the war, the M2 design was already obsolete with a 37 mm gun, 32 mm frontal armor, an impractical number of secondary machine guns and a very high silhouette. The Panzer III and Panzer IV's success in the French campaign led the U.S. Army to immediately order a new medium tank armed with a 75 mm gun in a turret. This would be the M4 Sherman. Until the Sherman reached production, an interim design with a 75 mm gun was urgently needed.
The M3 was the solution. The design was unusual because the main weapon — a larger caliber, low-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 were incapable of casting a turret big enough to hold the 75mm main gun. 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 seen on the French Char B1 and the Mark I version of the British Churchill tank. In each case, two weapons were mounted to give the tanks adequate capability in firing both anti-personnel high explosive ammunition and armor-piercing ammunition for anti-tank combat. The M3 differed slightly from this pattern having a main gun that could fire an armor-piercing projectile at a velocity high enough for efficiently 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 featuring a turreted gun. It was understood that the M3 design was flawed, but Britain urgently needed tanks. A draw-back 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 cage to the gearbox driving the front sprockets. Steering was by differential braking, with a turning circle of 37 ft (11 m). The vertical volute-sprung suspension (VVSS) units possessed a return roller mounted directly atop the main housing of each of the six suspension units (three per side), 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 was operated by a gunner and a loader. Sighting the 75-mm 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 3,000 yd (2,700 m) 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 37-mm was aimed through the M2 periscope, though this was mounted in the mantlet to the side of the gun. It also sighted the coaxial machine gun. Two range scales were provided: 0-1,500 yd (1,400 m) for the 37-mm and 0-1,000 yd (910 m) for the machine gun.
Though not at war, the U.S. was willing to produce, sell and ship 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 on the beaches near 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 lack of a radio in the turret (though the tank did have a radio down in the hull), the riveted armor plating (whose rivets tended to pop off inside the interior in a deadly ricochet when the tank was hit by a non-penetrating round), the smooth track design, insufficient armor plating and lack of splash-proofing of the joints. The British desired modifications for the tank they were purchasing. A bustle was to be made at the back of the turret to house the Wireless Set No. 19. The tank was to be given thicker armor plate than the original U.S. design, and the machine gun cupola was to be replaced with a simple hatch. With these modifications accepted, the British ordered 1,250 M3s. The order was subsequently increased with the expectation that when the M4 Sherman was available, it could replace part of the order. Contracts were arranged with three U.S. companies. The total cost of the order was approximately 240 million US dollars, the sum of all British funds in the US; it took the US Lend-Lease act to solve the financial shortfall.
The prototype 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, both the Lee and the Grant types would need to be accepted.
The U.S. military used the "M" (Model) letter to designate nearly all of their equipment. When the British Army received their new M3 medium tanks from the US, confusion immediately set in between the different M3 medium tank and M3 light tank. The British Army began naming their 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 M3 brought much-needed firepower to British forces in the North African desert campaign.
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.
Of the 6,258 M3s produced by the U.S., 2,855 were supplied to the British Army, and about 1,386 to the Soviet Union. The American M3 medium tank's first action during the war was in 1942, during the North African Campaign. British Lees and Grants were in action against Rommel's forces at the Battle of Gazala on 27 May that year. Their appearance was a surprise to the Germans, who were unprepared for the M3s 75 mm gun. They soon discovered the M3 could engage them beyond the effective range of their 5 cm Pak 38 anti-tank gun, and the 5 cm KwK 39 of the Panzer III, their main medium tank. The M3 was also vastly superior to the Fiat M13/40 and M14/41 tanks employed by the Italian troops, whose 47 mm gun was effective only at point blank range, while only the few Semoventi da 75/18 self-propelled guns were able to destroy it using HEAT rounds. In addition to the M3's 75 mm gun outranging the Panzers, they were equipped with high explosive shells to take out infantry and other soft targets, which previous British tanks lacked; upon the introduction of the M3, Rommel noted, "Up to May of 1942, our tanks had in general been superior in quality to the corresponding British types. This was now no longer true, at least not to the same extent." Despite the tank's advantages and surprise appearance during the Battle of Gazala, it could not win the battle for the British, as German doctrine to engage enemy tanks using anti-tank guns, such as the notorious 88 mm, proved too deadly for British armor that repeatedly charged without infantry or artillery support.
Grants and Lees served with the British in North Africa until the end of the campaign. Following Operation Torch (the invasion of French North Africa), the U.S. also fought in North Africa using the M3 Lee. The U.S. 1st Armored Division had given up their new M4 Shermans to the British prior to the Second Battle of El Alamein. Subsequently, a regiment of the division was still using the M3 Lee when they arrived to fight in North Africa. The M3 was generally appreciated during the North African campaign for its mechanical reliability, good armor protection and heavy firepower.
In all three areas, the M3 was able to engage German tanks and towed anti-tank guns. Yet the high silhouette and low, hull-mounted 75-mm were tactical drawbacks, since they prevented fighting from a hull-down firing position. The use of riveted hull superstructure armor on the early versions led to spalling, where the impact of enemy shells caused the rivets to break off and become projectiles inside the tank. Later models were built with all-welded armor to eliminate this problem. These lessons were applied to the design and production of the M4. The M3 was replaced by the M4 Sherman as soon as the M4 was available. Several specialist vehicles based on the M3 were employed in Europe, such as the M31 armored recovery vehicles and the Canal Defence Light.
Starting in 1941 1386 M3 tanks were shipped to the Soviet Union but the Red Army only received 976 of these as the rest were lost in marine transit. These were supplied through the Lend-Lease program in 1942-1943. All were Lee variants, although the Soviets sometimes referred to them generically as Grants. The M3 was unpopular in the Red Army, which already used the more modern T-34. The faults of the M3 Lee revealed themselves in engagements against enemy armor and anti-tank weapons; the Soviets gave it the nickname Братская могила на шестерых ("a grave for six"). The official Soviet designation was М3с (М3 средний, "M3 medium") to distinguish them from М3л (М3 лёгкий, "M3 light") Stuart tanks. With the Soviet Union producing close to 1,500 T-34s a month, their use of the M3 Lee declined after mid-1943. The Soviets still used them on secondary fronts, such as in the Arctic during the Red Army's Petsamo–Kirkenes Offensive in October 1944.
In the Pacific War, tank warfare played a secondary role as the primary battles were fought with naval and aerial forces. In the Pacific Ocean Theater and Southwest Pacific Theater, the U.S. Army deployed only a third of its 70 separate tank battalions, and none of its armored divisions, while the U.S. Marine Corps deployed all six of its tank battalions.
When the British Army received M4 Shermans, about 900 M3 tanks were transferred to the Indian Army and some of these saw action in the war in South East Asia. British Lees and Grants were used by the British Fourteenth Army until the fall of Rangoon, performing "admirably" in Burma in 1944-45, in its original role: supporting infantry. In the Far East, the M3's main task was infantry support. It played a pivotal role during the Battle of Imphal, during which the Imperial Japanese Army's 14th Tank Regiment (consisting of mostly captured British M3 Stuart light tanks and their own Type 95 Ha-Go light tanks) encountered M3 medium tanks for the first time and found itself outgunned and outmatched by the British armor. Despite their worse-than-average off-road performance, the M3s performed well as they traversed the steep hillsides around Imphal. Officially declared obsolete in April 1944, the Lee nevertheless saw action until the end of the war.
The Australian Army also received approximately 1,700 M3 Grants that had originally been part of a UK order. The Australian Armoured Corps had been formed in 1941 to take part in the North African Campaign, but was retained in Australia after the outbreak of hostilities with Japan. In 1941–42, the cadres of three armoured divisions were formed – all of them were equipped partly with the M3 Grant – in addition to M3 Stuart light tanks. In April and May 1942, the 1st Armoured Division's regiments began re-equipping with M3 Grants and completed their training in a series of large exercises around Narrabri, New South Wales. The 2nd and 3rd Armoured Divisions were officially formed in 1942 and were also partly equipped with M3 Grants. In January 1943, the main body of the 1st Armoured Division was deployed to home defence duties between Perth and Geraldton, Western Australia, where it formed part of III Corps. However, the Grants were deemed unsuitable for combat duties overseas and M3 units were re-equipped with the Matilda II before being deployed to the New Guinea and Borneo Campaigns. Due to personnel shortages, all three divisions were officially disbanded during 1943 and downgraded to brigade- and battalion-level units.
During the battle for Tarawa island in 1943, the US Army attacked nearby Makin Island, which was considered a less costly operation. The army was supported by a platoon of M3A5 Lee medium tanks from the US Army's 193rd Tank Battalion, making this battle the only combat use of the M3 by America in the Pacific Theater. The US Marine Corps did not use M3 Lees; their light tank battalions were equipped with M3 Stuarts until they were replaced by M4 Shermans in mid 1944.
During the war, the Australian Army had converted some M3 Grants for special purposes, including a small number of bulldozer variants, beach armoured recovery vehicles and wader prototypes.
Following the end of the war 14 of the Australian Grants were converted to a local self-propelled gun design, the Yeramba, becoming the only SPG ever deployed by the Australian Army. Fitted with a 25-pounder field gun, the Yerambas remained in service with the 22nd Field Regiment, Royal Australian Artillery, until the late 1950s.
Many M3s deemed surplus to Australian Army requirements were acquired by civilian buyers during the 1950s and 1960s for conversion to earthmoving equipment and/or tractors.
Overall, the M3 was able to cope with the battlefield of 1942. Its armor and firepower were the equal or superior to most of the threats it faced, especially in the Pacific. Long-range, high velocity guns were not yet common on German tanks in the African theater. However, the rapid pace of tank development meant that the M3 was very quickly outclassed. By mid-1942, with the introduction of the German Tiger I, the up-gunning of the Panzer IV to a long 75-mm gun, and the first appearance in 1943 of the Panther, along with the availability of large numbers of Shermans, the M3 was withdrawn from service in the European Theater.
British designations in parenthesesM3 (Lee I/Grant I)
Riveted hull, high profile turret, gasoline engine. 4,724 built.
M3A1 (Lee II)
Cast (rounded) upper hull. 300 built.
M3A2 (Lee III)
Welded (sharp edged) hull. Only 12 vehicles produced.
M3A3 (Lee IV/Lee V)
Twin GM 6-71 diesel variant of welded hull. Side doors welded shut or eliminated. 322 built.
M3A4 (Lee VI)
Stretched riveted hull, 1 x Chrysler A57 Multibank engine, made up of five 4.12 litre displacement, 6-cyl L-head car engines (block upwards) mated to a common crankshaft, displacement 21 litres, 470 hp (350 kW; 480 PS) at 2,700 rpm. Side doors eliminated. 109 built.
M3A5 (Grant II)
Twin GM 6-71 diesel variant of riveted hull M3. Although it had the original Lee
turret, it was referred by the British as Grant II
. 591 built.
M31 Tank Recovery Vehicle (Grant ARV I)
Based on M3 chassis, with dummy turret and dummy 75 gun. A 60,000 lb (27,000 kg) winch installed.
M31B1 Tank Recovery Vehicle
Based on M3A3.
M31B2 Tank Recovery Vehicle
Based on M3A5.
M33 Prime Mover
M31 TRV converted to the artillery tractor role, with turret and crane removed. 109 vehicles were converted in 1943-44.
105 mm Howitzer Motor Carriage M7 (Priest)
105 mm M1/M2 howitzer installed in open superstructure. A gunless version was used as an OP (observation post vehicle)
155 mm Gun Motor Carriage M12
Designed as the T6. A 155 mm howitzer on M3 chassis. 100 built in 1942-1943. M30 Cargo Carrier on same chassis to transport gun crew and ammunition.
Guns removed and replaced with armored recovery vehicle equipment.
Fitted with map table and extra radio equipment and having guns removed or replaced with dummies.
Grant Scorpion III
75 mm (3.0 in) gun removed, and fitted with Scorpion III mine flail, few made in early 1943 for use in North Africa.
Grant Scorpion IV
Scorpion III with additional motor to increase Scorpion flail power.
From "Canal Defence Light"; 37 mm (1.5 in) turret replaced by one with a powerful searchlight and a machine gun. 355 were also produced by the Americans, who designated it the Shop Tractor T10.
A single M3A5 was converted into a "Beach Armoured Recovery Vehicle".
Yeramba Self Propelled Gun.
Australian SP 25 pounder. 13 vehicles built in 1949 on M3A5 chassis in a conversion very similar to the Canadian Sexton.
Medium Tank M4 Sherman
Tank Cruiser, Ram - see article for full list of variants
105 mm Self Propelled Gun, Priest
Kangaroo armoured personnel carrier
25pdr SP, tracked, Sexton Mark I - Sexton Mark II was on a Grizzly chassis
M12 Gun Motor Carriage
China used during Burma campaign 1945
Romania 4 captured in the Crimea during operations in early 1944
In the 1943 movie Sahara, starring Humphrey Bogart, the character's main form of transportation was an M3 Lee named "Lulu Belle"; the same is true of the 1995 remake starring Jim Belushi.