ROMANUS I  . (Lecapenus), who shared the imperial throne with Constantine VII . (q.v.) and exercised all the real power from 919 to 944, was admiral of the Byzantine fleet on the Danube when, hearing of the defeat of the army at Achelous (917), he resolved to sail for Constantinople . After the marriage of his daughter Helena to Constantine he was first proclaimed " basileopater " in 919 and soon after crowned colleague of his son-in-law . His reign, which was uneventful, except for an attempt to check the accumulation of landed property, was terminated by his own sons, Stephen and Constantine, who in 944 carried him off to the island of Prote and compelled him to become a monk . He died in 948 .