On 4 April 1081, Alexios I Komnenos was crowned Byzantine emperor in Hagia Sophia at Constantinople, marking the beginning of the Komnenian dynasty.

Alexios had seized power three days earlier, on 1 April 1081, when supporters within the capital opened the gates of Constantinople to his forces. The reigning emperor Nikephoros III Botaneiates abdicated without significant resistance.

His accession came at a moment of profound crisis for the Byzantine Empire. The disastrous defeat at Manzikert in 1071 had opened much of Asia Minor to the Seljuk Turks, while the Normans under Robert Guiscard threatened the empire from the west.

Alexios’ coronation inaugurated a new ruling dynasty that would govern Byzantium for more than a century and initiate a period of political and military recovery.