Taking advantage of the disruption caused by the Fourth Crusade, he made himself independent, one of several local rulers that appeared throughout the Byzantine Empire during the final years of the Angeloi dynasty.

[2] In circa 1201/1202, when a rebellion in Thessaly and Macedonia led by Manuel Kamytzes and Dobromir Chrysos cut southern Greece off from Constantinople, several revolts broke out in the Peloponnese: Leo Chamaretos seized control of Sparta, Monemvasia was plagued by violent disputes among its leading families.

[7] Soon after, while the Byzantine government was preoccupied with the Fourth Crusade, Sgouros launched naval raids against Athens, enlisting the aid of the piratical inhabitants of the islands of Salamis and Aigina.

[6][7] In 1203, as Constantinople was threatened by the Fourth Crusade and despite Michael Choniates's entreaties, Sgouros moved against Athens, claiming that the city's inhabitants harboured a fugitive from justice.

[12][13] Sgouros was well on his way to forming an independent state of his own in southern Greece, which had every chance of becoming, in the words of the medievalist John Van Antwerp Fine, "a lasting affair", until the arrival of the Crusaders.

[12] Boniface's first assault on Sgouros's defenses in the Isthmus was repulsed, but the second broke through, and by spring 1205 he controlled the countryside of the northeastern Peloponnese, while the fortified cities held out against him.