The M5A1 Stuart is the second variant of the Light Tank M5 Stuart family. Originally developed from the Light Tank M3 Stuart family in response to the wartime shortage of the radial aero-engines used in the M3 light tanks, a new version with twin Cadillac V8 engines and dual Hydra-Matic gearboxes functioning through a transfer case was designed. This tank was quieter, cooler, and more spacious; the automatic transmission also made crew training faster. The new light tank (originally designated Light Tank M4 Stuart but subsequently referred to as Light Tank M5 Stuart to avoid confusion with the Medium Tank M4 Sherman) had a remodelled hull with a raised rear deck over the engine compartment, a sloped glacis plate, and driver's hatches moved to the top. In 1942, the M5 Stuart gradually replaced the M3 Stuart in production, and as the M7 light tank project proved undesirable, the Light Tank M24 Chaffee replaced the M5 Stuart in 1944. A total of 8,884 M5 and M5A1 tanks were manufactured. The 75 mm M8 howitzer motor carriage (M8 HMC) was also based on the M5 chassis with an open-top turret.

Introduced in Update 1.45 "Steel Generals", the M5A1 Stuart is a new series of light tanks developed from the Light Tank M3 Stuart family, and it shares many characteristics with other U.S. Army light tanks of rank I. In general, the M5 and M3 light tanks have similar playstyles. The M5A1 Stuart saw extensive use near the end of World War II, particularly in Normandy. They were designed to carry out scouting, reconnaissance, and infantry support rather than engage in tank-to-tank combat with enemies. They heavily resemble the M3A3 Stuart used by the Chinese Nationalist Army during World War II and the Chinese Civil War in appearance.