The battle of Tall as-Sultan (22 April 1176) was a major victory won by Saladin during his conquest of Syria, and saw him defeat the allied armies of Aleppo and Mosul.
After the death of Nur ad-Din in May 1174 his Syria kingdom quickly split into three factions, based at Damascus, Aleppo and Mosul. Aleppo gained possession of as-Salih, Nur-ad-Din's young son and heir. Mosul was ruled by Nur-ad-Din's nephew Saif-ad-Din. Damascus was left feeling vulnerable and the ruling elite of the city asked Saladin to take power. Saladin reached Damascus in October 1174. A first attempt to take Aleppo failed, and he was faced by an alliance between Aleppo and Mosul. He defeated the allies at the battle of the Horns of Hamah (13 April 1175). In the aftermath of this battle the authorities in Aleppo agreed to recognise Saladin as the independent ruler of Damascus, Egypt and the areas he had conquered from Aleppo.
Saif-ad-Din had not been present at the battle, and he refused to accept the peace agreement. He opened negotiations with his former general Gümüshtigin, now a senior figure in Aleppo and a new alliance was born. An ambassador was sent on a round trip of the major Syrian capitals, with orders to negotiate an alliance with Aleppo then move to Damascus to reassure Saladin that Saif-ad-Din intended to accept the earlier peace agreement. According to one source the ambassador accidently handed Saladin Aleppo's message to Mosul, thus alerting him to the plot.
Even if this story isn’t true Saladin did discover the plot and was able to summon reinforcements from Egypt. He then led his army north to intercept the armies of Aleppo and Mosul. By this point Saif-ad-Din and the forces from Aleppo had joined up, and were moving south.
Saladin's scouting let him down, and on 21 April Saif-ad-Din ran into Saladin's army while it was scattered and his men were watering their horses. Saif-ad-Din had a chance to win an easy victory, but remarkably he threw it all away. Despite all of his successes Saladin was still seen as an upstart Kurd, while Saif-ad-Din was a member of the Turkish elite and of the Zengid dynasty. He is reputed to have said 'Why should we inconvenience ourselves over the destruction of this upstart? Tomorrow will be soon enough'.
It wasn't. Saladin used the time to move onto the hill of Tall as-Sultan, giving him a strong defensive position. An easy victory was thus turned into a hard-fought battle.
The battle was fought on 22 April 1176. Saif-ad-Din had the best of the early fighting, and Saladin's left wing was pushed back (either by the lord of Irbil, or by Muzzafer ed-Din, lord of Harran (later one of Saladin's main supporters). Saladin led his own guard into the fight on his left, stopped the enemy advance and then forced them back. Saif-ad-Din's line collapsed after this setback and his army was routed. Saladin took a large number of prisoners and Saif-ad-Din was forced to retreat back towards Mosul.
In the aftermath of the battle Saladin captured Saif-ad-Din's camp. According to the historian Ibn Abi Tayy Saif ad-Din had over one hundred female singers with his army, along with vast amounts of wine. Saladin allowed his men to claim most of the booty in the camp, while he only took a set of bird cages, which he sent back to Saif-ad-Din with the suggestion that he stick to more gentle pursuits than war.
In the aftermath of the battle Saladin released the most important of the prisoners, beginning the process of winning them over to his side. He briefly appeared outside Aleppo, before moving north to capture Manbij. He then besieged Azaz (15 May-21 June 1176), to the north-west of Aleppo before turning back to Aleppo. This time the authorities were unwilling to risk a siege and on 29 July they signed a treaty in which Saladin was recognised as king in Damascus and Egypt. Azaz was returned to them. Saladin was now secure in Damascus, and was free to return to Egypt after a three year absence.