Kerak was the stronghold of Raynald of Chatillon, Lord of Oultrejordain, 124km South of Amman . The fortress was built in 1142 by Pagan the Butler, Lord of Montreal . While Raynald ruled, several truces existed between the Christian and Muslim states in the Holy Land, none of which he made any qualms about breaking. The last straw came in 1183 when he organized an expedition around the Red Sea. He captured the town of Aqaba, giving him a base of operations against Islam's holiest city, Mecca. Saladin, the leader of the Muslim forces, could not tolerate this and moved against Raynald's stronghold.
Inside the walls, a royal marriage was taking place. Humphrey IV of Toron, Raynald's stepson and heir was to take the hand of Isabella of Jerusalem, the King's stepsister. As the wedding ceremonies continued, Saladin instructed his troops to avoid bombarding the young couple's quarters, but pressure on Kerak continued. Messengers managed to escape the town and take word to the King, Baldwin IV.
Baldwin immediately marched with a relief force, accompanied by his regent, Raymond III of Tripoli. Although suffering from leprosy since childhood, Baldwin's determination to frustrate Saladin's attempt was such that he led personally, although he had to be carried on a stretcher. The Christian forces arrived while Saladin was still struggling against the heavy fortifications. Knowing he risked being crushed between the Royal army and the walls of Kerak, he fled.
The King of Jerusalem had withstood his Muslim rival for the time being, although it was clear he would not survive for much longer, so aggressive was his disease. Just 5 years later, with Saladin's great rival gone, the Kingdom would crumble.
The motion picture Kingdom of Heaven contains a fictional portrayal of the siege, in which the Knights of Ibelin and the Ayyubids engage in battle. In the film, the Knights attacked so defenseless citizens could retreat to Raynald's castle.