1086–1093) was a prominent Byzantine military leader on land and sea during the early reign of Emperor Alexios I Komnenos (r. 1081–1118), especially in the campaigns against Tzachas of Smyrna.
According to the Alexiad, Constantine Dalassenos was related to Alexios I through his mother, Anna Dalassene, although the exact connection is unknown.
[1][2] He first appears in 1086/7, when he was sent as an envoy to receive Sinope and the surrounding towns from a Turkish chiaus who had turned renegade, had become baptized and collaborated with the Byzantines.
[3][4] In spring 1090, Dalassenos was raised to the post of "doux of the fleet" and given command of the Byzantine naval forces against the emir Tzachas of Smyrna.
[1][2] Taking advantage of Tzachas's absence in Smyrna, Dalassenos disembarked his troops on Chios and immediately assailed the island's fortified capital.
The siege lasted for three months, before Tzachas offered to surrender the town in exchange for safe passage back to Smyrna.