Order 66 was the order Chancellor Palpatine gave the Grand Army of the Republic in Episode III: Revenge of the Sith. It was one of several contingency orders given to the Clone Troopers, which they were trained to follow without question in case of an emergency. Order 66, which could only be executed on Palpatine’s direct command, called for the Clone Troopers to kill their Jedi leaders. Ostensibly in place to prevent the Jedi from turning against the Republic, Order 66 was really Palpatine’s plan to eliminate the Jedi Order so the Sith could take power.