Changing of the Guard

"This is unprecedented. Unacceptable."

- Special Operations Commander Rtas 'Vadumee

Though there were many causes for the Great Schism, some old and some recent, the Changing of the Guard was the final spark that ignited the conflict.

After the assassination of the Prophet of Regret by the Demon, the Hierarchs, believing that the Elites were no longer capable of protecting the Prophets, reassigned the Elite Honor Guards, replacing them instead with Brutes. This was in flagrant violation of the Writ of Union, the founding document of the Covenant, and was a direct insult to the Elites as a people, who threatened to resign. In their place, the Brute Honor Guardsmen Taking this opportunity, the Prophets declared the Elites to be traitors to the Covenant, encouraging the other races to turn against their former commanders and remain loyal to the Prophets, igniting the Civil War.

However, the Prophets had not foreseen the support the Elites still had among much of the Covenant. Many Grunts and Hunters broke away with the Elites, joining the Separatists, and the conflict between them and the Loyalists began the Great Schism.

Trivia

 * The High Prophet of Truth actually indistinctly entitled the event as a "Exchange of Hats"
 * "Changing of the Guard" is a known phrase in modern-day England. It signifies the time when the guards protecting the queen trade shifts. This is a similar process that occured between the Sangheili and the Jiralhanae.