Because of the restrictions that only the infantry could use tanks, the US. Cavalry looked for possibilities to get tanks as well. In 1931 General Douglas MacArthur talked the Army into the use of 'Combat Cars' for the cavalry ('tanks' would be exclusive for the infantry). Around 1934-35 a couple of experimental light tanks were produced, the T2, T2E1 and the T2E2. This would lead for the cavalry to the T5. The T5 was further developed into the T5E2, that became the M1 Combat Car (are you still with me?) The M1 had a 7 cylinder Continental W670 radial engine. The turret had a .50 and a .30 inch caliber machinegun. There was an additional .30 at the front of the hull.

The next version, the M2 had improved maneuverability. In July, 1940 a new Armored Force was founded and the development went from then hand in hand between the infantry and the cavalry, and the 'Combat Cars' were from then on 'tanks'. The M1 and the M2 became the M1A1 and the M1A2. These light tanks saw never action, but were important in training crews and further development. Main engine for the M2A2E3 and the M2A3E3 became the Guiberson diesel engine which gave the vehicle a greater radius.

The last of the M2 series, the M2A4 got a 37mm canon in the turret. An order for 329 tanks was given to the American Car Foundry in October, 1939. The first was delivered in April, 1940. The order was extended to 365 vehicles, the last was delivered in March, 1941. The M2A4 was deployed in the Pacific Ocean, but was mainly used as trainer vehicle.

The Light Tank M3 was a further development of the concept M1 and had still the Continental W670 as engine. The armor became thicker. To compensate the weight, the suspension had to be built stronger. The older version had still 'gunports' in the turret, in the M3 these were abandoned. In March, 1941, the M3 went into production again at the American Car Foundry. During the production adjustments were made, such as a whole welded turret instead of the riveted one. This was a great step forward in reducing the weight without losing armor thickness. Half way 1941 the canon got a stabilizer. The British Army used the M3 in North Africa under the name 'Stuart' Mk I. They made some important adjustments, such as the additional fuel tanks that could be jettisoned, larger fenders and smokepots on the turret. The name 'Stuart', used by the Brits, was not the only one,… crews named her affectionately 'Honey'. The American crews had no special name for her, other than abusive ones because of the cramped space in the vehicle.

There were 5811 M3's produced until January 1943. Of these, 1834 went to the British army who deployed the little tank mostly in Africa. The Soviet Union's Red Army got 1336 M3's. Because of the demand of the aircraft industry for the Continental engines, 1285 M3's were delivered with the Guiberson T1020 diesel engine.

A important improvement led to the M3A1. The turret was completely redeveloped. It lost the extra cupola and could rotate electrically. The new turret got an internal basket for the crew to sit in. In the previous models, the crew, loader and gunner, had to 'walk' with the turret when it was in motion and had to step over the crankshaft housing.

Until the introduction of the turret basket, it was common to maneuver the complete tank in the direction of fire. But not every crew was happy with the 'basket', the space was more cramped and often the crew removed it.

Later models of the M3A1 lost the two extra machineguns sideways in the hull, that were remotely operated by the driver in the M2A4 and the M3. They were of limited use and the Brits had removed them mostly already in the predecessors. From the 4621 M3A1 built, 1594 went to the British and 1676 went to the Soviet Union. A total of 4410 M3A1's had the Continetal and 211 had the Guiberson diesel engine.

More developments resulted in M3A3, the final version. This type had a welded hull and the position of the driver was moved forward and somewhat higher. It could also take more ammunition and fuel on board. The turret was enlarged and therefor the radio could move to the back of the turret. The M3 models before the M3A3 had pistol ports, these were deleted in the new turret. Of the M3A3 were 3427 built, and the British army received 2045 of them. The M3A3 was almost exclusively produced for the Lend-Lease and served, besides the British, with the Commonwealth, Soviet Union and the Chinese. The American army only used a handful.

Because the gun proved too light in action against enemy tanks, the turret was sometimes removed altogether, so it could be used for a fast troop vehicle (Kangaroo), ambulance or, with extra communication apparatus, as a commander vehicle.

A proposal of Cadillac, a unit of the GMC group, to give an M3 a double Cadillac V8 engine was accepted in 1941 by the Ordnance Department. A standard M3 was converted to accept the 'Twin'Cadillac and a commercial used transmission was built into the vehicle. To take away any doubt, if there was any with the Ordnance Department, the M3E2 made a 500 mile trouble free testdrive between Detroit and Aberdeen at a speed of 50 miles an hour.

A new light tank was born and went into production. First as 'Light Tank M4', but it was changed in Light Tank M5 (the British Stuart VI) because of the confusion with the Medium Tank M4 (Sherman).
The back of the M5 was raised to house the Cadillac engines. Also the upgraded M3A3 (Stuart Mk V) was used to develop the M5, which led to the M5A1 in September, 1942. Both tanks had a sloping hull at the front with enlarged hatches for the driver and co-driver. A better watertight sealing was improved and on the back of the turret was room created for the radio.

Early 1943 the M5A1 took the production line in favor of the M5. Around 7000 were built of the M5 versions. They served until the end of the Second World War when the M24 Chaffee Light Tank appeared in 1944 in Europe.

The M5 was always on the frontline with reconnaissance units. It was a agile vehicle and with her speed of 45 miles an hour and her firepower it gave good support to the up-front recce teams. The firepower and armor was inadequate against German panzer, but against enemy infantry and light vehicles it was a great little tank.

An important version of the M5A1 was the M8 Howitser Motor Carriage. It had a 75mm howitzer in an open turret. In 1944-45 they operated in conjunction with Medium Tank Battalions of Headquarter Companies to give extra support

Some testing was done to see if it could carry a 75mm canon instead of the 75mm howitzer. It was a test with satisfaction, but there was no room left for enough ammunition and the armor was inadequate for further development.

Worldwide there are still some M3 and M5 Light tanks left, and some are restored to drive. In Normandy are a few on display, like the M3A3 at Musée Le Grand Bunker in Ouistreham, and an M5A1 at the Musée de Epaves sous-marines de Débarquement near Port-en-Bessin, which was recovered from the sea.