Emperor John proceeded to lay siege to Dorostolon, which lasted for sixty five days. His army was reinforced by a fleet of 300 ships equipped with Greek fire. There were several engagements before the walls of the city, which demonstrated to the Byzantines that the Rus' lacked skill in cavalry warfare. Among the casualties were the Emperor's relative, Ioannes Kourkouas (whose severed head was displayed by the Rus from one of the towers) and the second-in-command in Svyatoslav's army, a certain Ikmor (who was killed by Anemas, a son of the Cretan emir, in revenge for Ikmor's assassination of his father during the Byzantine siege of Crete).