Nur ad-Din unites Muslim Syria

When Zengi was killed in September 1146 his realm was divided: his eldest son Sayf ad-Din Ghazi took Mosul, while Nur ad-Din, then twenty-eight, took the signet ring from his father's hand and made for Aleppo. That autumn Count Joscelin II briefly retook the town of Edessa, though not its citadel; Nur ad-Din drove him out, and his troops massacred and enslaved the Armenian townspeople who had sided with the Franks. When the Second Crusade, launched to avenge Edessa, turned instead against Damascus in July 1148, the siege collapsed after a few days, on 28 July. On 29 June 1149 Nur ad-Din destroyed the army of Antioch at Inab, where Prince Raymond of Poitiers was killed, and rode to the coast to bathe in the Mediterranean as a sign of his mastery; in 1150 Joscelin II fell into his hands and died in his prison at Aleppo, and the last remnants of the County of Edessa were lost.

Damascus, whose rulers had allied with Jerusalem against Zengi, was the last obstacle. Nur ad-Din besieged it in vain in 1150 and 1151, but in April 1154, helped by its inhabitants, he took the city and sent its Burid ruler Mujir ad-Din Abaq away to Homs; Muslim Syria, from Edessa to the Hauran, was united under him, and Mosul, too, recognised his overlordship. In 1164 he routed the princes of northern Syria at Harim, capturing Raymond III of Tripoli, Bohemond III of Antioch and Joscelin III, and from 1164 to 1169 his Kurdish general Shirkuh, accompanied by his nephew Saladin, fought the Franks for Egypt, where the Fatimid regime was falling apart. In January 1169 Shirkuh became vizier in Cairo, and two months later Saladin succeeded him.

Nur ad-Din cultivated the image of a just Sunni ruler and leader of the struggle against the Franks. He founded madrasas, hospitals — among them the Nur al-Din Bimaristan in Damascus — and caravanserais, sat in regular sessions to hear complaints against his own officials and in 1148 banned the Shi'ite call to prayer in Aleppo. In 1168–1169 he had a magnificent carved wooden minbar made in Aleppo for the al-Aqsa Mosque, to be installed once Jerusalem was retaken. He pressed Saladin to end the Fatimid caliphate, which Saladin did in 1171, but relations between the two soured, and Nur ad-Din was preparing to march on Egypt when he died in the citadel of Damascus on 15 May 1174. Saladin completed his work: he entered Damascus that same year and installed Nur ad-Din's minbar in al-Aqsa after the conquest of Jerusalem in 1187.