War of Beginnings

"So full of hate were our eyes that none of us could see. Our war would yield countless dead, but never victory."

- Covenant Writ of Union

The Sangheili-San'Shyuum war was an interstellar war set between the Sangheili and the San'Shyuum races, over religious and technological differences. At the conclusion of the war, the Writ of Union was penned and initiated, and the Covenant was kindled.

Prelude
After leaving their homeworld Janjur Qom in 2100 BCE, the San'Shyuum encountered the Sangheili in 938 BCE, who also had experience with Forerunner technology. The San'Shyuum believed that incorporating Forerunner technology was allowed by their religion. To the Sangheili, such a thing would have been unthinkable heresy. The San'Shyuum attempted diplomacy with the Sangheili; they sent a delegation to explain that they, too, worshiped the Forerunners. The Sangheili summarily executed the delegation, thus beginning the hostilities.

War
During the combat, the Sangheili had an early advantage, with each warrior comparable in skill to several San'Shyuum in battle. However, the San'Shyuum's technological superiority, and possession of the Forerunner Dreadnought, meant that they had the advantage in space battles, using the Dreadnought to great effect in devastating hit-and-run strikes against the Sangheili war fleets. Eventually in 876 BCE, in order to ensure the survival of their race, the Sangheili were forced to amend their position of the treatment of Forerunner technologies and began studying their relics and incorporating elements into their warship, weapon and armor designs. The San'Shyuum also realized that if there were other races with martial capabilities like the Sangheili, they would be in serious danger.

The Writ of Union
"So let us cast arms aside, and like discard our wrath. Thou, in faith, will keep us safe, whilst we find the Path."

- Covenant Writ of Union

In time, the Sangheili learned of the San'Shyuum's belief in the Great Journey, where the Forerunners used the Halo Array to ascend to a god-like state, and wished to repeat this process on themselves. Coupled with this belief and the fact that the cause of war was obsolete, the Sangheili agreed to unite with the San'Shyuum into an alliance to avoid mutual extinction. In 852 BCE, the two races signed a treaty known as the Writ of Union to form the early Covenant, which defined the two races' positions: the San'Shyuum would act as the religious leaders, studying the Forerunners' technology and seeking out the Halos, while the Sangheili would serve as their protectors, using weapons and technology developed by the San'Shyuum. The Dreadnought was decommissioned and made the center point and power source of High Charity, a mobile planetoid which would serve as the capital of the Covenant.

Ussa 'Xellus' insurgency
While most Sangheili willingly—or begrudgingly—joined the new Covenant, there were those who resented what they viewed as submission to the San'Shyuum. The Covenant sought to make an example of these dissenters, silencing those who rejected the new union with overwhelming force. The resistance movement would come to be led by the Sangheili Ussa 'Xellus, a skilled strategist and veteran of the war. After the Xellus keep was attacked by a Covenant air raid, the civil war expanded across Sanghelios. Because of their inferior numbers 'Xellus and his followers were soon driven into hiding in the desolate region of Nwari. However, 'Xellus would travel across Sangheili colonies, looking for dissidents he could recruit to his cause. After the like-minded elder Sangheili 'Crecka showed him Shield World 0673, 'Xellus intended to make the Forerunner world his new base of operations and home for his people.

List of appearances

 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo: Broken Circle