Conrad regarded himself the ruler of Tyre, forbidding Guy of Lusignan to enter the town in summer 1189. Guy laid siege to Acre, but James of Avesnes, Louis III of Thuringia and other crusader commanders who came to the Holy Land also questioned his claim to leadership. Guy's wife, Sybilla, and their two daughters died in autumn 1190. Guy's opponents argued that he had only been king by marriage, and his wife's half-sister, Isabella, inherited the crown. Guy did not want to abandon his claim to the Kingdom of Jerusalem. Taking advantage of the situation, Conrad of Montferrat decided to marry Isabella.