The M3 Stuart, officially Light Tank, M3, was an American light tank of World War II. An improved version entered service as M5. It was supplied to British and other Commonwealth forces under lend-lease prior to the entry of the U.S. into the war. The British service name "Stuart" came from the American Civil War Confederate general J. E. B. Stuart and was used for both the M3 and the derivative M5 Light Tank. In U.S. use, the tanks were officially known as "Light Tank M3" and "Light Tank M5".
When the U.S. Army joined the North African Campaign in late 1942, Stuart units still formed a large part of its armor strength. After the disastrous Battle of Kasserine Pass, the U.S. quickly followed the British in disbanding most of their light tank battalions and subordinating the Stuarts to medium tank battalions performing the traditional cavalry missions of scouting and screening. For the rest of the war, most U.S. tank battalions had three companies of M4 Shermans and one company of M3s or M5/M5A1s. In Europe, Allied light tanks had to be given cavalry and infantry fire support roles since their main cannon armament could not compete with heavier enemy armored fighting vehicles. However, the Stuart was still effective in combat in the Pacific Theater, as Japanese tanks were both relatively rare and were lighter in armor than even Allied light tanks. Japanese infantrymen were not well equipped with anti-tank weapons, and as such had to use close assault tactics. In this environment, the Stuart was only moderately more vulnerable than medium tanks.
Though the Stuart was to be completely replaced by the newer M24 Chaffee, the number of M3s/M5s produced was so great (over 25,000 including the 75mm HMC M8) that the tank remained in service until the end of the war, and well after. With the limitations of both the main gun and armor, the Stuart's combat role in Western Europe was severely hampered. Light tank companies were often paired with cavalry reconnaissance units, or else used for guarding or screening, and even used in supply or messengers roles for medium tank units.