 The Crusaders wrested control of Gaza from the Fatimids in 1100. According to the chronicler William of Tyre, the Crusaders found it uninhabited and in ruins. Unable to totally refortify the hilltop on which Gaza was built, due to a lack of resources, King Baldwin III built a small castle there in 1149. The possession of Gaza completed the military encirclement of the Fatimid-held city of Ascalon to the north. After the castle's construction, Baldwin granted it and the surrounding region to the Knights Templar. He also had the Great Mosque converted into the Cathedral of Saint John.
