In 1147, as part of the ''Reconquista'', crusader knights led by Afonso I of Portugal besieged and reconquered Lisbon. The city, with around 154,000 residents at the time, was returned to Christian rule. The reconquest of Portugal and re-establishment of Christianity is one of the most significant events in Lisbon's history, described in the chronicle ''Expugnatione Lyxbonensi'', which describes, among other incidents, how the local bishop was killed by the crusaders and the city's residents prayed to the Virgin Mary as it happened. Some of the Muslim residents converted to Roman Catholicism and most of those who did not convert fled to other parts of the Islamic world, primarily Muslim Spain and North Africa. All mosques were either completely destroyed or converted into churches. As a result of the end of Muslim rule, spoken Arabic quickly lost its place in the everyday life of the city and disappeared altogether.