The M3 Medium Tank

A good enough tank for the time being

M3 “Lee” Medium Tank at Fort Knox
(Photo: Alfred T
. Palmer)

The adage "a bird in the hand is worth two in the bush" often holds acutely true in wartime. A solution that works decently enough and is available quickly is often preferable to one which promises better results but much further down the line. Weapon development in World War II was full of quick, "good enough for now" designs whose quality ranged from abysmal failures to unexpected but stellar successes. The topic of today's article, the American Medium Tank, M3, also commonly known as the Lee and the Grant, is not only an example of a decent stopgap solution, but is also one of (if not the) most distinctive-looking tanks of the war.

A ”Grant Command” version of the M3 in British use. The 37 mm gun is replaced with a dummy, and there’s a map table and extra radio equipment inside.

The M3 was born out of two problems: America's failure to keep up with tank design between the World Wars, and Britain's acute need for tanks when much of the army's equipment was abandoned during the fall of France, and U.K. Forces were pushed hard by Germany and Italy in Africa.

In 1939, the U.S. had about 400 tanks, most of them M2 Light Tanks, with a small number of "modern" M2 Medium Tanks. "Modern" was not only a greatly relative term here, but completely misplaced. It was a tall target, poorly armored, and essentially worked as a mobile platform for seven machine guns (an unnecessarily high number), while its 37 mm main gun was quite inadequate by the time World War II broke out. This inadequacy became obvious when reports from Germany's rapid and unstoppable invasion of France started coming in. The Army was desperate to develop a new tank which could stand up to German Panzer III-s and IV-s (Read our earlier article), and which could be manufactured quickly.

M2A1 medium tanks, the unsuccessful predecessors of the M3
(Photo: U.S. Army Signal Corps)

Analysis of the Battle of France convinced the Army that the new tank needed a 75 mm main gun, but the M2's turret could not hold a weapon of that size, and the design and production of a new, larger turret would have taken too long. As it happened, the M2 already had an experimental version which had a howitzer gun built into the hull itself. This was used as an inspiration for a new tank which had a 75 mm gun (based on an old French design and the same gun a later version of which would eventually go into the Sherman (Read our earlier article). Evoking World War I designs, the gun was placed in a sponson on the tank's right side, which greatly limited its firing arc. The turret was retained from the M2, but initially only armed with a single .30 caliber machine gun (Read our earlier article) to take out enemy infantry around the tank. This was rather silly, and a 37 mm gun was eventually placed in the turret. The idea was that the 75 mm gun would destroy enemy tanks and fixed fortifications, while the 37 mm on the top would use its 360° arc of fire to eliminate fast-moving but lightly armored vehicles. A small cupola was placed atop the turret, with the possibility to mount a machine gun on it. In fact, the early version of the tank could theoretically carry up to eight .30 cals, though such a loadout was extremely rare in practice. The Ordnance Department was given a mere 60 days to design the new tank.

Frontal view of the M3 
(Photo: Library of Congress)

One good thing about the Medium Tank, M3 was that unlike earlier tanks, its main gun could fire both armor piercing shells against tanks and high explosive ones against softer targets, which gave the gun and the vehicle significant versatility by the standards of the time. It was also mechanically reliable, and its armor proved to be quite sufficient against most German and Italian tanks it encountered early in the war. The M3 could engage targets from outside the effective range of the German Pak 38 anti-tank gun, and the Panzer III's KwK 39 gun.

Top view of the original M3 version, highlighting the asymmetrical construction
(Photo: War Department manual TM 9-750)

Having said that, the M3 also had its share of problems. One was the unusually large height of 10 feet (3 m), which made it an easy target. Additionally, its main (and only genuinely useful) gun was located not up in the turret, but halfway up the tank. This meant that an M3 in hull-down position, hiding behind a hill, mount or some other obstacle with only the turret popping up over it, could not fire the gun, since the obstacle was in the way. The tank had to roll forward and further up to fire, exposing more of itself to the enemy. Another problem was the relatively weak engine which made the vehicle sluggish. Later versions were given various upgrades. One was a collection of five 6-cylinder automobile engines attached to the gear shaft, designed because of a shortage of tank engines, and posing a nightmare to mechanics. The side doors were a weak point, and were removed in later versions to increase crew protection.

M3A1 with its distinctive and rare cast upper hull at Fort Knox, 1942
(Photo: U.S. Army)

Another weakness of the tank was the assembly of the hull. The first and several later versions had the hull plates riveted in place. Riveting, however, represents a danger in tank design due to an effect called spalling: a high explosive shell hitting the armor from the outside might not penetrate it, but it will cause pieces of the rivet to break loose and fly off in the crew compartment, possibly wounding or even killing crewmen. Welding is a more secure solution and was used in several versions of the tank, but welding heavy armor plates secure required a know-how American factories didn't have early in the war. Some 300 M3s were produced with single-piece cast upper hulls, but only one factory used the technology and the tanks were never used operationally.

An M3’s armor plates being riveted in place at the Detroit Tank Arsenal. The massive horseshoe-shaped device is the riveting apparatus.
(Photo: Alfred T. Palmer)

The M3 originally had a crew of seven: commander, 37 mm gunner and 37 mm loader in the turret, 75 mm gunner, 75 mm loader, driver and radio operator in the hull. This was a bit excessive, and the radioman was eventually eliminated, giving his job to the driver.

The M3 was recognized to be a flawed design from the start, but it was needed urgently. When the M3's design process began in July 1940, the M4 was already scheduled for production, relegating the M3 to a stopgap measure. However, not everyone could wait for the M4: Britain had lost much of its hardware during the flight from France, and was hard-pressed in Africa. They were originally hoping to have American factories build British-designed tanks, but this proposal was rejected. They settled on the M3 instead. Britain spent 240 million dollars, the entire sum of money held by the British government in the U.S. to order 500 tanks from each of four American companies under the Cash and Carry system. From early 1941 onward, additional orders were handled under the Lend-Lease system.

Crewmen evacuating a “disabled” M3 during the Third Louisiana Maneuvers, 1943
(Photo: U.S. Army Signal Corps)

One company, the Lima Locomotive Company, took its sweet time getting underway with the work. By the time they finished the steam engines they were building, cleared out enough factory floor space and tooled up for tank production, the M3 was already on the way out and no more were needed. The company's tardiness ended with an unexpected reward, rather than punishment: once production of the M4 Sherman started, the other companies were too busy building M3-s, and Lima Locomotive could get in on the Sherman production early. Over the course of the war, five factories produced M3s, the most productive being Chrysler's Detroit Tank Arsenal, which made over half of the 6,258 M3's built. On an interesting minor note, two of the factories engaged in a bit of harmless dishonesty in the earliest stages of production, when parts shortages were a major problem. The American Locomotive Company finished its first M3 tank in early 1941, and drove it past some senior officials in a small ceremony. Once the ceremony was over, they removed the transmission and sent it to the Baldwin Locomotive Works who installed it in their first tank completed for a similar ceremony.

M3 Lees under construction at the Detroit Arsenal
(Photo: Alfred T. Palmer)

The British required some changes to the original American design of the M3. Most notably, British-ordered turrets had the cupola removed and replaced with a simple hatch – it’s been suggested that the removal was necessary to make the tank fit through British railway tunnels. Meanwhile, the turret itself was made bulkier. This made it possible to give it thicker armor, mount a smoke grenade launcher, and to replace the American radio in the hull with a British set inside the turret. This way, the commander of British M3s could double as the radio operator (while American tanks had the driver do that), eliminating one crewman.

The first M3 built to British specifications at the Pressed Steel Car Company. July 15, 1941

The British were also responsible for coming up with the tank's popular names. American tanks in British service were named after Civil War generals; the American version of the M3 Medium Tank was dubbed the "General Lee," while the version in British use was the "General Grant" – these two names were later shortened to Lee and Grant. Many “Lee” tanks were handed down to the British later during the war when American units started replacing the design with the Sherman, so the United Kingdom eventually ended up with examples of both types.

The British “Grant” (left) and American “Lee” (right) versions of the M3 et El Alamein in 1942. The difference in turret shape is clearly visible.
(Photo: Imperial War Museum)

The Grant first saw combat in North Africa with British forces, at the Battle of Gazala in Libya in May 1942. The battle was actually a defeat for the British and led to the Axis capture of Tobruk, but the M3 Grant acquitted itself well, surprising the Germans with the range and power of its gun. German General Erwin Rommel  (Read our earlier article)  himself 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."

A British Grant with a knocked-out Panzer one during the Battle of Gazala
(Photo: Imperial War Museums)

The M3 went on to serve well in North Africa until the arrival of the Sherman, but was declared obsolete by 1943 and replaced with its successor as soon as it became available. 1,386 tanks were sent to the Soviet Union as Lend-Lease (with 417 of them lost to German attacks on the convoys) but proved unpopular in the East. By this time, the Panzer IV was upgraded with a better gun, and the Tiger tank had also appeared on the battlefields, rendering the M3 outclassed, and allegedly earning it the Soviet nickname "Grave for Seven Brothers." Once T-34 production was in full swing, the remaining M3s were moved to backwater areas and fronts with less intensive fighting, where their main enemies were old French tanks captured by the Germans.

Tankers of the Soviet 6th Guard Army with M3s during the Battle of Kursk
(Photo: Red Army)

Lees and Grants continued to see action in the Pacific and Southeast-Asia against Japanese forces, whose tanks were few and poorly armored. Lees fought in some operations during the island-hopping campaign, and Grants were put to good use in Burma.

A British M3 in Mandalay, Burma, early 1945, with additional tracks welded to the front glacis for extra protection
(Photo: Imperial War Museums) 

While the M3 was removed from combat duty, several versions of it continued to see use, mainly tank recovery vehicles and prime movers. Several vehicles were based on the M3 chassis, most notably the M7 Priests self-propelled gun, the Canadian Ram tank (only used for training), and some versions of the Kangaroo troop carrier. The tank was also used for some of the Canal Defense Lights, special-purpose vehicles serving with Hobart's Funnies (Read our earlier article) designed to blind the enemy with a strong spotlight. The little-known Yeramba was an Australian self-propelled howitzer artillery piece built in the late 1940s; it was based on the M3, and retains the distinction of being the only self-propelled artillery in Australian service to this day.

Prototype of the Australian Yeramba, based on the M3 Medium Tank
(Photo: Australian War Memorial)

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