Order 66

Order 66, also known as Clone Protocol 66, Protocol 66, or simply "the Order," was one of the top-secret contingency orders that identified all Jedi as traitors to the Galactic Republic and, therefore, subject to summary execution by the Grand Army of the Republic. The order was programmed into the Grand Army clone troopers through behavioral modification biochips implanted in their brains from creation, making it almost impossible for the clones to disobey the command to turn against their Jedi Generals. The Kaminoan scientists who designed the clone troopers were deceived into believing it was only to be used as a contingency protocol against renegade Jedi. In secret, Order 66 was the means by which the Sith intended to bring about the long-awaited fall of the Jedi Order.

During the Clone Wars, the Sith agenda was progressing relatively unnoticed until a premature activation of Order 66 resulted in the death of General Tiplar at the hands of Tup, a defective clone whose malfunctioning chip caused him to betray and kill his Jedi officer. The incident led ARC trooper Fives to conduct his own investigation into the matter, believing the incident to be a Separatist plot against the Republic. On the galactic capital Coruscant, however, he learned that the chips conditioned the clones to become hostile against the Jedi. Furthermore, he discovered to an extent Supreme Chancellor Sheev Palpatine's involvement in the conspiracy and attempted to assassinate him. Fives told what he knew to his Jedi superior Anakin Skywalker, but he could not prove it, and he was killed by clone shock troopers of the Coruscant Guard.

The plan continued apace for the remainder of the war, although the Jedi High Council had grown increasingly wary of the Chancellor's motives. In 19 BBY, a group of Jedi Masters sought to arrest Palpatine upon learning his true identity as the Sith Lord Darth Sidious. When their efforts failed, Palpatine used the incident to deceitfully frame the Jedi Order for treason and, as such, forcibly compelled the clone army to execute their Jedi commanding officers in accordance with Order 66.

Across the galaxy, thousands of Jedi were betrayed and killed by their own troops while the Chancellor's new apprentice, the Sith Lord Darth Vader, formerly Jedi Knight Anakin Skywalker, led the 501st Legion in a direct assault on the Jedi Temple of Coruscant. With the exception of a few surviving Jedi, such as Grand Master Yoda, Jedi Master Obi-Wan Kenobi, former Padawan Ahsoka Tano, Padawans Kanan Jarrus and Cal Kestis, and Jedi Knight Cere Junda, as well as Kelleran Beq and youngling Grogu, the Great Jedi Purge was largely accomplished through the initial activation of Order 66. Even after the initial onslaught, Order 66 still stood, and all Jedi, even people who were merely suspected of being Jedi, were to be summarily killed on sight, without requiring evidence or explanation as to why the kill was carried out. Sidious would go on to consolidate his reign as Emperor of the Galactic Empire, ruling for decades until the prophecy of the Chosen One came to pass, marking the end of the Sith and the restoration of balance in the Force by 4 ABY.

Text and facts from the “Order 66” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.