The siege of Aleppo (30 December 1174-March 1175) was Saladin's first attempt to capture Aleppo and take control of Nur ad-Din's young son and heir (Saladin's Conquest of Syria). Nur ad-Din had died in May 1174 and his kingdom quickly began to unravel. By the end of July his nephew Saif-ad-Din of Mosul was ravaging the northern lands of Aleppo, the rulers of Damascus had sought an alliance with the Franks and the rulers of Aleppo had control of the young king as-Salih. The authorities in Damascus then invited Saladin to come from Egypt to take over. He arrived on 28 October, after a rapid journey, and took firm control in the city.
Saladin's next target was Aleppo and with it control of the young king. He sent a message to as-Salih asking him to choice Saladin as his protector. The authorities in Aleppo sent an insulting reply back to Damascus. This triggered an immediate response, and after only ten days at Damascus Saladin set out to attack Aleppo.
On 9 December Saladin's army captured the city of Homs, but the citadel held out. He then moved on to Hamah. There the governor agreed to put Saladin's case at Aleppo, but when he arrived at the city he was arrested. His brother handed the city over to Saladin, who then moved on to Aleppo, arriving on 30 December 1174.
The defenders made good use of as-Salih, parading him through the city to remind the defenders that they were fighting for Nur ad-Din's son and legitimate heir.
The defenders of Aleppo, led by Gümüshtigin, searched for possible allies in every direction. They came to terms with Sinan, the leader of the Assassin sect. Sinan and Nur ad-Din had been enemies, so this move weakened the credibility of the Aleppo regime. Sinan sent his assassins to try and kill Saladin and in early January 1175 they came close to success, but the last of them was intercepted just outside his tent.
Gümüshtigin also turned to the Franks. After the death of King Amalric, Jerusalem was controlled by the competent regent Raymond of Tripoli. Raymond led the Crusader army to Homs, where it combined with the garrison in the citadel to threaten the troops that Saladin had left there. This forced Saladin to lift his siege of Aleppo and move south to rescue his troops at Homs. The Franks withdrew as Saladin approached, and in mid March the citadel finally fell to him. He then captured Baalbek.
These successes forced Saif-ad-Din to take Saladin seriously. He now agreed to join the forces of Aleppo and attempt to defeat the upstart Saladin. The resulting battle of the Horns of Hamat (13 April 1175) was a major victory for Saladin, and helped secure his position in Syria.