 At the peak of his power, he even declared himself Byzantine emperor, and sought to assault Constantinople in conjunction with the Pechenegs.In 1092, a Byzantine naval expedition under John Doukas inflicted a heavy defeat on him and retook Lesbos, while in the next year he was treacherously slain by his son-in-law Kilij Arslan I. Smyrna and the rest of Tzachas' former domain were recovered by the Byzantines a few years later, in 1097.Very little is known about his life, and that mostly from only one source, the "Alexiad" of the Byzantine princess Anna Komnene, daughter of Emperor Alexios I Komnenos ().