Thel 'Vadam

Thel 'Vadam was a skilled fleet commander, warrior, and politician who was best known for being the last Arbiter of the Covenant, and the first leader of the Concord of Reconciliation. He would later be known by the epithet Schism Arbiter for both his key involvement in the Great Schism, from its onset to organizing and mediating the Schism Councils.

Human-Covenant War
Thel 'Vadam's greatest victories were seen during the Fall of Reach. In command of a large coalition of naval formations that were organized under the Combined Fleet of Righteous Immolation, and armed with weeks of accurate intelligence reports on the planet's defenses, he attacked the colony on August 30, 2552. By skilfully coordinating his forces and organizing the ground campaign to begin at the same time as the orbital battle, as well as utilizing his skill at lightning attacks, most of Reach's defenses were divided and overwhelmed on the first day. Elements of his fleet were dispatched to destroy evacuating starships, while he remained to coordinate the attacks in Epsilon Eridani. On late August 31, news reached him that one of these battle groups discovered one of the fabled Halos - Installation 04 in the Soell system. He immediately took what remained of the Fleet of Particular Justice and swiftly made his way there. Controversially, Thel did not inform the other fleetmasters why he was leaving, as he desired to claim credit for discovering and securing the megastructure himself.