Baldwin IV (1161-1185), the son of Amalric I of Jerusalem and his first wife Agnes of Edessa, was king of Jerusalem from 1174 to 1183, when he had his nephew Baldwin V crowned in his place.
Baldwin IV was educated by William of Tyre, and came to the throne at the age of thirteen. Because he was not old enough to rule by himself the kingdom came under the regency of Raymond III of Tripoli. Fortunately, the greatest enemy of the kingdom at this time, Saladin, was distracted from the weakness of Jerusalem by the sons of Nur ad-Din, from whom he was attempting to take the territory they had inherited from their father. He did not achieve this until 1183, leaving Jerusalem in relative peace.
Meanwhile Baldwin faced distractions of his own, from his sister Sibylla and Raynald of Chatillon, the former prince of Antioch through marriage to Constance (1153—1159). Since 1160 Raynald had been a prisoner in Aleppo, and after his release in 1176, had become lord of the fortress of Kerak, to the east of the Dead Sea. With Raynald, Baldwin defeated Saladin at the Battle of Montgisard in 1177, but Raynald persistently provoked Saladin by attacking Muslim caravans.
Sibylla was the heiress of the kingdom, so her marriage was important. Raymond III arranged for her to marry William of Montferrat, with whom she had a son, the future Baldwin V. After William's death in 1177, she married Guy of Lusignan in 1180. Guy and Sibylla quickly began to plot against Baldwin, who, although he was now old enough to rule on his own, was incapacitated with leprosy. They allied with Raynald, who was by now taking advantage of his position at Kerak to harass the trading caravans travelling between Egypt and Damascus. After Saladin retaliated for these attacks in 1182, Baldwin named Guy regent, but Guy refused to fight Saladin and Saladin's troops simply went home. In 1183 Guy and Sibylla had Baldwin name Baldwin V the new king, and appointed Raymond III regent for his nephew in 1184. He died in 1185.