Lil' Louie is an M60 Patton. The M60 Patton, officially the 105 mm Gun Full Tracked Combat Tank. M60 Patton is a main battle tank (MBT) introduced in December 1960. It was widely used by the U.S. and its Cold War allies.
This Patton was operated by Mitch during his time with the Army. After the outbreak, he used it to survive until he met up with Martinez. He now keeps it parked at the camp. The Governor uses it in his attack on the Prison, first as a show of force to get Rick and his group to leave. When they refuse, the tank smashes through the fences and destroys several parts of the prison with its main gun. The Governor's militia uses the tank as mobile cover. The tank eventually stops in the courtyard, where Daryl rolls a grenade into the main gun's barrel, destroying it.