 It has been suggested that the death in 888 of Cerball mac Dúnlainge, who may have been the true overlord of Dublin at this time, acted as a catalyst for Flann Sinna's attempt to conquer the city.In 888 Sichfrith Ivarsson was assassinated by his brother Sitric I, who held the throne for five years (888–893).During this time the Dubliners were strong enough to carry out successful raids on major monasteries.