As in Africa, dynastic struggles in Ostrogothic Italy provided an opportunity for intervention. The young king Athalaric had died on 2 October 534, and a usurper, Theodahad, had imprisoned queen Amalasuntha, Theodoric's daughter and mother of Athalaric, on the island of Martana in Lake Bolsena, where he had her assassinated in 535. Thereupon Belisarius, with 7,500 men, invaded Sicily (535) and advanced into Italy, sacking Naples and capturing Rome on 9 December 536. By that time Theodahad had been deposed by the Ostrogothic army, who had elected Vitigis as their new king. He gathered a large army and besieged Rome from February 537 to March 538 without being able to retake the city.