|The following is based on Fallout Tactics and some details might contradict canon.|
The tank is a drivable vehicle in Fallout Tactics: Brotherhood of Steel.
The tank is a heavily modified M4 Sherman battle tank, which has seen extensive modification over the years. Although woefully outdated by the 21st century, in the resource-deprived reality of the wastelands, it is a veritable juggernaut. It is heavy, yes, and very slow, yes, but the sloped steel armor makes it nigh invulnerable to most infantry weapons, short of explosives and anti-tank weaponry. It retains its primary 75mm gun mounted on a fully traversing turret, with a gyrostabilizer enabling the crew to fire with reasonable accuracy while the tank was on the move. However, the range of the gun was reduced severely when raiders tried to rebore the barrel and failed.
The Brotherhood recovered the tank and pressed it into service. The tank became the unofficial flagship of the Brotherhood's vehicle fleet, bearing its insignia proudly on the most vital of fronts. The original crew was killed in a search and rescue operation in Newton, where the Brotherhood attempted to extract Reaver Movement leaders in the face of a massed robot invasion. However, the Eastern Brotherhood of Steel does not give up easily. The Warrior's squad was deployed to the city and recovered the tank, using it to great effect against the robotic forces.
The tank is the most powerful weapon in the Warrior's arsenal. Although it cannot pack as many troops as the APC, it has a mounted weapon, firing ports, and plenty of armor for cracking robot strong points. Unfortunately, it cannot be brought to bear in subsequent storyline missions.
Note that for the purposes of determining accuracy with the gun, the game will test the pilot's Big Guns skill, rather than the gunner's.
Tank appears only in Fallout Tactics.