In 1161, Simon was invited by
Matthew Bonnellus to lead a rebellion in
Palermo against King William I. Simon allied with his nephew,
Tancred of Lecce (the illegitimate son of Roger of Apulia). On 9 March 1161, Simon and Tancred seized the royal palace, detaining King William,
Queen Margaret, and their two sons. During the uprising, a massacre of Muslims in Palermo was instigated. Initially, rebels considered crowning the young
Roger IV, Duke of Apulia, but popular sentiment shifted towards making Simon king. Before Simon could secure his claim, the rebellion collapsed. The rebels released the royal family and retreated. In exchange for a pardon, Simon and others accepted exile from the kingdom. ==Later life==