War of Beginnings

The War of Beginnings was the first inter-species war between the Sangheili and San'Shyuum, and was the epoch of the Covenant.

Striking the heart
For much of the battling the Irshun League was neutral. However, seeing the potential to damage their geopolitical rivals and the possibility of getting ahead of them, the Irshun League decided to side with the San'Shyuum. Their proximity to the other Sangheili powers allowed them to strike far deeper into both.

Exodus
Many in the Thar'shi Sphere and Crimson League could not stand to be under this new Covenant, prompting numerous desertions and disappearances. A prominent figure to do so was Ussa 'Xellus.