Great Schism

The Great Schism, also known as the Great Betrayal among the sangheili, was a major civil war between the forces loyal to the Covenant against the Covenant Separatists during the final cycles of the Ninth Age of Reclamation. During the Schism, three major factions fought for victory: the sangheili Fleet of Retribution; the remnants of the Covenant led by the san'shyuum and the jiralhanae; and the Flood, which took over the Covenant holy city of High Charity in an effort to assimilate the other warring factions. The Schism marked both the end of the Covenant and the partition of its client species for a thousand years.