Order 66

Order 66, also known as Clone Protocol 66, was one of the 150 Contingency Orders of the Grand Army of the Republic which all Clone Troopers were trained to obey by way of a biochip implanted in their brains. The order mandated that the Jedi Order attempted to stage a coup against the Galactic Republic, and all Jedi were to be executed immediately. The biochips implanted within the Clone Troopers activate when Darth Sidious as Chancellor Palpatine sends a message to execute Order 66 to all Clone Commanders when the time has come.

It was during the Battle of Umbara that General Pong Krell foresaw the fall of the Jedi and Order 66, so he decided to sabotage the Republic's war efforts.