In 1066, according to the "Breve chronicon Northmannicum", Maurex (Mambrica/Mambrita) commanded a fleet that stopped an attempted invasion of the Balkans by Count Geoffrey of Taranto, and in the next year, at the head of a Byzantine army he landed in Apulia and took Bari, Taranto and Castellaneta from the Normans. He could not prevent the Normans from besieging Bari again in 1068, however, and in 1070, he is recorded as fighting against Geoffrey and Robert Guiscard.