Mandalorian–Ithullan war

In retaliation, a group of rogue Jedi Knights allied with the Gen'Dai bounty hunter Durge against the orders of the Jedi Council, and assassinated the ruling Mand'alor, leader of the Mandalorian clans, nearly a hundred years later.

The genocide of the Ithullan species led to a large number of Mandalorian soldiers growing dissatisfied with their out-of-control, immoral contemporaries. This desire for change was taken to heart by Jaster Mereel, who instituted a new standard of behavior for the Mandalorian warrior clans when he rose to the position of Mand'alor in 60 BBY. Mereel authored the Supercommando Codex, a new standard for Mandalorian ethics, which stated that any Mandalorian who wished to fight were to conduct themselves as honorable mercenaries.