General Kade was a Sontaran who invaded Chelsea 426 after the population there was infected by specialised spores that possessed the citizens of the colony, turning them into puppets of the Rutan Host.
He was the commanding officer of the Fourth Sontaran Intelligence Division. He made all citizens of Chelsea 426 undergo certain tests to ascertain whether or not they were under the influence of the Rutan Host.
His subordinate, Colonel Sarg — who thought the best course of action was to destroy Chelsea 426 and all of its inhabitants (a course of action shaped by the time Sarg spent with one of the many Sontaran Battle Fleets) — challenged General Kade's authority, claiming that he had the support of many of the Sontarans under Kade's command.
General Kade accepted Sarg's challenge, engaging his subordinate in a duel for control of the Fourth Sontaran Intelligence Division — a duel which could only end with the death of either General Kade or Colonel Sarg.