A nobleman Alexios Doukas (nicknamed Mourtzouphlos) became the leader of the anti-crusader faction within the Byzantine leadership. While holding the court rank of "protovestilarios", Doukas had led Byzantine forces during the initial clashes with the crusaders, winning respect from both military and populace. He was accordingly well-placed to move against the increasingly isolated Alexios IV, whom he overthrew, imprisoned, and had strangled in early February. Doukas then was crowned as Emperor Alexios V. He immediately moved to have the city fortifications strengthened and summoned additional forces to the city.