The Last Castle (2001)

Plot:

Three-star General Irwin, a renowned military tactician, has been court-martialed and sentenced to a maximum security military prison run with an iron fist by its warden, Colonel Winter. Winter can't help but respect the once-legendary general, but that respect turns to hostility as Irwin defiantly confronts the warden on his methods. Their confrontation escalates into war when the general organizes his fellow inmates into an army to take over the prison.