Last Stand: Bolos 4

Controlled by their tireless electronic brains which were programmed to admit no possibility of defeat, the gigantic robot tanks known as Bolos were almost indestructible, and nearly unstoppable. Almost. Nearly. A sufficiently determined enemy armed with nearly limitless firepower and willing to sustain terrible losses could destroy a Bolo. But even a terminally damaged Bolo is still an opponent to reckon with, and as long as a Bolo's artificial intelligence retains a flicker of consciousness, its indomitable drive to defend the human race against all enemies will propel it forward. Bolos can be destroyed--but they never surrender!