The Tank Lords (Baen)

Colonel Alois Hammer has welded five thousand killers into a weapon more deadly than any other in the human universe. When a planetary government faces threats from guerillas, insurgents or terrorists, the men they hire are Hammer's Slammers, known throughout the galaxy for their cold, ruthless ferocity, their ability to defeat overwhelming forces and their willingness to go up against impossible odds. How do they do it? They certainly don't abide by the rules of civilised warfare ...but then nobody ever claimed that the Hammers were nice! Even when their chances are one step away from hopeless - those who oppose them have no chance at all...