Tech Tree: (Unconfirmed) 2nd Britsh Medium Tree
This tank appeared for a brief moment in a video that also showcased the French super-heavies.
Wikipedia Information: The Medium Tank M3 was an American tank used during World War II. In Britain the tank was called by two names based on the turret configuration. Tanks employing US pattern turrets were called the "General Lee", named after Confederate General Robert E. Lee. Variants using British pattern turrets were known as "General Grant", named after U.S. General Ulysses S. Grant.
Design commenced in July 1940, and the first M3s were operational in late 1941. The U.S. Army needed a good tank and coupled with United Kingdom's demand for 3,650 medium tanks immediately, the Lee began production by late 1940. The M3 was well armed and armored for the period, but due to design flaws (high silhouette, archaic sponson mounting of the main gun, below-average off-road performance) it was not satisfactory and was withdrawn from front line duty as soon as the M4 Sherman became available in large numbers.