Nur ad-Din moves north to Antioch, with assistance from his brother Qutb ad-Din in Mosul, his other vassals from Aleppo and Damascus, and the Artuqids of the Jazira, and besieges the fortress of Harim (Harenc) in 1164.
As William of Tyre says, "he stationed his engines around it in the customary manner and began to assault the place with a fury which permitted the inhabitants no rest."
Reginald of Saint Valery, lord of Harim, calls for help, and Raymond III of Tripoli, Bohemond III of Antioch, and Joscelin III of Edessa arrived to relieve the siege.
They are joined by Constantine Kalamanos, the imperial governor of Cilicia, and Thoros, and Mleh of Armenia, as well as Hugh VIII of Lusignan and Geoffrey Martel, brother of William IV of Angoulême, both of whom had recently arrived on pilgrimage.
Nur ad-Din prepares to give up the siege when they arrive, but the crusaders, inspired by the victory at al-Buqaia, and, "regardless of the rules of military discipline ... recklessly dispersed and roved hither and yon in pursuit of the foe."
Nur ad-Din's troops defend against their charge and lead a counterattack, pushing the crusaders into a swamp, and they are massacred "like victims before the altar."
It is possible that Nur ad-Din was only feigning a retreat in order to draw the crusaders into an ambush, but abandoning a siege when a relief army arrived is a standard tactic and Nur ad-Din presumably had no way of knowing the crusaders would follow him.
William's assertion that this was a reckless move is further evidence of this.
"Only the Armenian Thoros, who had foreseen the Turkish maneuver and had not set off in pursuit, escaped from the disaster".
(Oldenbourg, Zoé (1966).
The Crusades.
New York: Pantheon Books.)
Mleh also avoids capture.
Constantine Kalamanos, Hugh, Raymond, Bohemund, and Joscelin are captured and imprisoned in Aleppo.
According to Ibn al-Athir, ten thousand crusaders were killed.
Nur ad-Din resumes the siege and captures Harim a few days later.