 John was probably still "doux" of Dyrrhachium in 1105/06, when he is recorded by Anna Komnene to have been defeated in a campaign against the Dalmatians.As the threat of a renewed Norman invasion by Bohemond loomed, the emperor replaced John with his younger brother Alexios.In , John married Maria Doukaina, daughter of the "protostrator" Michael Doukas, a brother of Alexios I's empress Irene Doukaina.