The American Car & Foundry began production of the M3 in 1941. It was designed to replace the older M2 Light Tank which was outdated, but it kept the same 37mm main gun. The M3 had a gasoline powered, 262 hp, air-cooled, Continental W-670-9A engine and it had a crew of 4.
The max speed was 57 km/h and the max range was about 112.6 kilometers (70 miles). The M3's armament consisted of its 37mm main gun and 5 Browning M1919A4 machine guns placed throughout the tank; the M3's weight was about 12,700 kg. It also had a length of 4.53m and it was 2.2m wide.
The armor had a thickness of about 3.8cm in the front, 2.5cm in the sides, and 2.5cm in the rear. As most tanks, the M3's weakest area was the top; it only had about 1.3cm of armor. It also had a fuel capacity of about 151 liters and an ammunition capacity of 103 37mm rounds. The M3 was sent to several countries and was modified most notably by Great Britain where it was designated the Stuart I.
The M3A1 was the next version of the Stuart after the M3 and it began production in 1942. The M3A1 had a new gyrostabilized gun and it had a new radio system. The M3A1 had more of its models made with a Guiberson T1020 engine then the original M3 and this engine was powered by diesel. It also had a 5 speed forward, 1 speed backwards transmission which was the same as the M3. Another new feature of the M3A1 is the redesigned turret which included an added periscope. The hull of the M3A1 was all riveted and the total weight of the new design is about 12,900 kg. The Stuart II which is the British modified version of the M3, had little changes besides the fact that it used the Guiberson T1020 engine more than the gasoline engine. This was the same differences with the Stuart III and the Stuart IV, a different engine.
The M3A3 was standardized in 1942 and it featured a new turret design, plus a new storage area in the rear of thetank. Among the upgrades in the turret, there is a bulge in the back that allows for the radios to be installed and also there is thicker armor. The armor in the front is around 4.4 cm thick and the sides, rear, and top have around the same thickness as the original M3. The weight is 14,402 kg and the length is 4.53m.
Just like the other models of the M3, the M3A3 is also designated the Stuart V and this version can have the Guiberson diesel engine commonly used by British forces. The M5 began production in 1942 and the main new difference between itself and the M3A3 is that it has liquid-cooled, twin Cadillac series 42 engines. The M5 had to have a modified rear deck and fuel tanks had to repositioned in order to accommodate the new engines. The new engine was because there weren't enough radial engines. The weight of the M5 was about 14,900 kg and the M5 could store up to 123 37mm rounds. As the previous models, the M5 was used by British forces and was designated the Stuart VI.
The M5A1 had begun production in late 1942 and it had a bulge in the redesigned turret which allowed for more space for the commander and the gunner. Another new feature is a spotlight and the tank is completely welded. The weight of the M5A1 is about 15,400 kg and the length is about 4.8m. It could carry around 147 rounds of ammunition for the 37mm main gun and about 6,500 rounds of ammunition for its several machine guns. It also had a 4 speed forward, 1 speed backward transmission.The M5 Stuart had several variants for a number of purposes besides being a light tank. These included included a command tank version, the T27 Mortar Motor Carriage, an M5 equipped with a flamethrower, The M8 Howitzer Motor Carriage, and an M5 equipped with rocket launchers. The M5A1 also had some subvariants which included 4 different versions of the M5A1 with a flamethrower.
The M3 Stuart and all of its variants were used in many different fronts in WWII including the Pacific, Eastern Front, and the Western Front. Some of the battles it fought in include the Battle of Guadalcanal and The Breakout from Normandy operations that followed D-Day. Other operations included those in North Africa, where the M3 served under British forces. Some British soldiers nicknamed it "Honey". The M3 gained a good reputation under British forces and it not only served with them in North Africa and Normandy, but in Burma.