Excerpts from Books and Wikipedia
"Early in 1187, the baron Reynald de Chatillon broke a truce by attacking a Muslim caravan. When Saladin responded by laying siege to Tiberias, King Guy of Jerusalem abandoned a strong defensive position near Nazareth and marched to relieve the city. Harried by Muslim forces, the crusaders made slow progress and were forced to stop for the night of July 3. They had run out of water and the Muslims lit grass fires around the hill to torment them. When dawn broke on July 4, the crusaders found themselves surrounded. King Guy was taken prisoner and only a handful of the crusaders escaped. Jerusalem, left defenseless by this entirely avoidable disaster, surrendered on October 2." [Furtado: 1001 Days] Baldwin IV had appointed Raymond of Tripoli to serve as regent and rule after his death. Raymond was fluent in Arabic and willing to explore peaceful coexistence. Guy de Lusignan was the choice of a group of nobles who favored a hostile approach--they staged a coup and ousted Raymond. Reynald of Chatillon was in the pro-war faction and continued to raid Muslim caravans despite a truce with Saladin." [Aldrete: Decisive Battles]