Saladin's Conquest of Syria, which took from 1174 to 1185, established him as the ruler of a powerful empire that included Egypt, Syria and parts of Mesopotamia, and that gave him a real chance of crushing the Crusader states.
At the time of Saladin's birth control of Muslim Syria was split between the Turkish ruler Zengi, who controlled Aleppo and Mosul, and the rulers of Damascus. Zengi died in 1146 and his empire split. Mosul went to his older son, Saif ad-Din, and Aleppo to his second son, Nur ad-Din. This divide didn't last long. Saif ad-Din died in 1149 and his successor acknowledged Nur ad-Din as his superior. Damascus fell to him in 1154, giving Nur ad-Din control of all of Syria. Egypt officially became part of his empire after three wars between 1164 and 1169, giving Nur ad-Din control of a large part of the Muslim world.
At the time of his death in 1174 Nur ad-Din ruled Damascus and Aleppo directly, while his nephew Saif-ad-Din ruled Mosul under him. Saladin was officially in the same position in Egypt, but there was little trust between the two regimes.
Nur ad-Din's kingdom began to fall apart soon after his death. His heir, as-Salih, was a boy of eleven and this led to an almost inevitable struggle for power.
At the time of his father's death as-Salih was in Damascus. The authorities at Damascus appointed a regent, and briefly held an advantage. At Aleppo the sons of Ibn-ad-Dayah, one of Nur ad-Din's key advisors, seized power and attempted to convince the new king to join them.
While the authorities in Syria worried about Saladin, the first revolt against the young king came from Saif-ad-Din. The ruler of Mosul was already on the march when Nur ad-Din died, coming to join a probable expedition against Saladin. Saif-ad-Din split his army. He led most of it on an invasion of northern Syria, conquering a series of cities that had previously been loyal to Nur ad-Din. A second contingent, under his army commander Gümüshtigin, was sent to Aleppo.
Gümüshtigin soon seized power in Aleppo. The existing regime had convinced as-Salih to move to Aleppo. Gümüshtigin made sure he was the leader of the expedition sent to collect the king. On his return to Aleppo, with the young king under his command, Gümüshtigin arrested the Dayah brothers and seized power.
The authorities in Damascus were now faced with two problems. Gümüshtigin and the young king at Aleppo threatened from one direction. In the west Amalric king of Jerusalem decided to take advantage of the death of Nur ad-Din and advanced to attack the border fortress at Banyan. Ibn-al-Muqaddam, the Damascene regent, moved against Amalric, but instead of fighting the two sides agreed an alliance. The value of this alliance was reduced by the death of Amalric on 11 July, but it still held.
Nur ad-Din had died in May as the ruler of a united kingdom. By mid July that unity had collapsed. His own nephew was attacking the outlying possessions of Aleppo. The rulers of Aleppo were preparing to attack Damascus and the authorities in Damascus had made an alliance with the Franks. Finally Saladin was looming just off the stage, posing a threat to the entire Zengid dynasty.
Nur ad-Din died in the middle of a crisis in Egypt. Saladin's enemies had finally decided to move against him. Former supporters of the Fatimid regime had planned to revolt in Cairo and at Aswan in the far south, while Amalric of Jerusalem and William II of Sicily were to attack in the north. This might have been a dangerous plan, but Saladin's agents discovered the plot in March, arrested the key plotters in Cairo, and in April they were executed. Amalric died on 11 July, so his invasion faded away. The Sicilians arrived at a fully prepared Alexandria in late July and were repulsed after a very short siege. The revolt at Aswan broke out late, and had been suppressed by September.
In the meantime Saladin had been unable to intervene personally in Syria. He officially acknowledged as-Salih as king, adding his name to the prayers in Cairo. He wrote letters to the authorities in Syria in which he proclaimed both his loyalty to Nur ad-Din and his obvious suitability to be regent for the new king.
Saladin's big break came in Damascus. Ibn-al-Muqaddam attempted to come to terms with Saif-ad-Din of Mosul, but when this failed he changed tack entirely and wrote to Saladin inviting him to take control of Damascus. This came just as Saladin was freed of concerns in Egypt and he acted quickly. He left Egypt at the head of a light force of 700 cavalry and reached Damascus on 28 October. Saladin's achievements in Egypt meant that he was already popular with the general population. Saladin appointed his brother Tughtigin as governor of Damascus. He then had a fiery interview with an ambassador from Aleppo, which triggered a new campaign.
After spending only ten days at Damascus, Saladin departed to make a first attempt to capture Aleppo. On 9 December he took the town of Homs, but the citadel held out. At Hamah the governor agreed to put Saladin's case at Aleppo and surrender the town if he was refused. The governor was arrested, and his brother surrendered Hamah to Saladin.
On 30 December Saladin's army reached Aleppo and began his first siege of the city. The defenders realised that they couldn't hope to defeat Saladin without allies. First they contacted Sinan, the leader of the Assassins, but an attempt to murder Saladin in his tents in January 1175 failed. Next they arranged an alliance with the Franks. Raymond of Tripoli, regent of the kingdom of Jerusalem, led an army to Homs. Saladin was forced to lift the siege of Aleppo, and marched to Homs. The Franks withdrew and Saladin was able to capture the citadel. He then took Baalbek, giving him control of all of Syria south of Hamah.
Saladin's successes finally forced Saif-ad-Din of Mosul to take him seriously and abandon his campaign of conquest in northern Syria. Saladin had already partly undermined his position by recruiting his brother Imad-ad-Din. This forced Saif-ad-Din to split his army. He led part of it to deal with his rebel brother, while the rest of the army, under Izz-ad-Din¸ another of his brothers, was sent to join the army of Aleppo.
The combined armies of Aleppo and Mosul advanced towards Saladin, who waited at Hamah. The two sides then began negotiations. Saladin knew that he was in a fairly weak position, with most of his army still on its way from Egypt, so he agreed to recognise as-Salih as king, acknowledge the overall supremacy of Aleppo and restore Homs, Hamah and Baalbek and rule Damascus as governor for as-Salih. His opponents then overplayed their hand, and demanded that he hand back Rahba. This town had belonged to Saladin's uncle Shirkuh and had been confiscated by Nur ad-Din. Saladin had restored it to Shirkuh's son, and couldn't go back on that without losing a great deal of prestige. He rejected this last demand, and a battle became inevitable.
The battle of the Horns of Hamah (13 April 1175) was fought around two hills, the horns. Saladin's outnumbered troops occupied the hills, but they were hard-pressed until reinforcements arrived. The tide then turned and Saladin won a major victory.
In the aftermath of this victory Saladin imposed surprisingly mild terms. His independent authority in Damascus and Egypt was recognised. In return he acknowledged the independence of Aleppo and the rule of as-Salih. Aleppo had to support Saladin in any war against the Franks. Saladin's new authority was confirmed by the caliph at Baghdad, who was delighted to have gained a powerful new supporter in Syria.
This peace was short-lived. Saif-ad-Din had no intention of sticking to the agreement, and was soon trying to arrange a fresh alliance with Aleppo. Gümüshtigin was reconciled with his former commander, and Aleppo and Mosul agreed to unite and attack Saladin.
Somehow Saladin discovered their plot. One Muslim source has the ambassador from Mosul accidently handing Saladin the official response to Saif-ad-Din from Aleppo instead of the false message of peace he had been sent to deliver. Whatever really happened Saladin had time to summon reinforcements from Egypt. Saladin then moved north to intercept the new allies.
On 21 April Saladin was badly caught out - his army was spread out watering its horses when Saif-ad-Din's army arrived on the scene. If Saif-ad-Din had attacked immediately then Saladin would probably have been defeated, but instead he decided to wait until the following day. This allowed Saladin to occupy the hill of Tall as-Sultan. The resulting battle of Tall as-Sultan (22 April 1176) ended as another victory for Saladin. Saif-ad-Din's camp was captured, as were many of his officers.
Four days later Saladin appeared outside Aleppo, but this time he didn't risk a siege. Instead he moved north to capture Manbij, then west to besiege Azaz (15 May-21 June 1176). During this siege the Assassins made a second attempt on his life, and managed to get into his tent.
After the fall of Azaz Saladin turned back to Aleppo. Gümüshtigin was away from the city, and the defenders were unwilling to endure another siege. Instead they offered to come to terms, and on 29 July a treaty was signed in which as-Salih acknowledged Saladin as king in Damascus and Egypt. Azaz was returned to Aleppo after as-Salih's sister was sent to plead with Saladin.
This agreement only left Mosul in active opposition to Saladin, but for the next few years Syria was more peaceful. Saladin returned to Egypt, and in 1177 launched his first major attack on the Crusader kingdom. This ended in defeat at Ramlah or Mons Gisardi, but the conflict continued at a lower level.
Syria remained quiet until the death of as-Salih, aged only eighteen, in December 1181. Saif-ad-Din had also died, and Mosul was now ruled by his brother 'Izz-ad-Din. Another possible candidate for the throne was their brother 'Imad-ad-Din, ruler of Sinjar. Inevitably as-Salih's court was split. One, 'Turkish' party wanted 'Izz ad-Din, on the grounds that he was the stronger of the two and would thus have a better chance of resisting Saladin. The second party, 'Arabic' party, didn't want to come under the control of Mosul and thus preferred 'Imad-ad-Din.
As-Salih himself had favoured 'Izz ad-Din, and his support probably helped swing things in favour of the ruler of Mosul. The Turkish party would soon be disappointed by their man. 'Imad ad-Din had little interest in Aleppo. He moved to the city, stropped the treasury and the armoury and then forced his brother 'Imad ad-Din to swap Sinjar for Aleppo. Aleppo was thus in a worse position than if they had simply invited 'Imad ad-Din to take power. 'Izz ad-Din retained some sort of claim to Aleppo, which would later cause problems in negotiations with Saladin.
The change of power at Aleppo angered Saladin, who had his own claim to the city, backed by a diploma from the caliph in Baghdad. He gathered an army in Egypt, and on 11 May 1182 left Cairo for the last time, at the head of 5,000 men. The Crusaders attempted to intercept this army as it marched to Damascus but without success. Saladin then carried out two raids into the Crusader kingdoms, fighting an inconclusive battle in June and failing to take Beirut in July 1182.
After this brief interlude Saladin returned to the power-battle in Syria. In September he arrived outside Aleppo, where he attempted to negotiate a settlement. While he was at Aleppo a delegation reached him from a number of 'Imad ad-Din's vassals in Mesopotamia. The plotters were led by the Lord of Harran, a city on the upper Euphrates. He gained the support of the lord of Hisn Kaifa, a city upstream of Mosul on the Tigris and of al-Birah, on the Euphrates.
The allies asked for assistance from Saladin. He agreed to support the and in October he crossed the Euphrates. He was acknowledged by the rulers of Edessa, Saruj and Nisibin, suggesting a northern route across upper Mesopotamia (the province of al-Jazirah), before in November his army arrived outside Mosul.
The main focus of this siege of Mosul was a series of negotiations between Saladin, 'Izz ad-Din and a representative of the Caliph at Baghdad. Saladin wanted 'Izz ad-Din to acknowledge him as his superior, to agree to provide troops for the Holy War, and to abandon his claims to Aleppo. The Caliph wanted to avoid conflict so close to the borders of his own powerbase around Baghdad. 'Izz ad-Din was unwilling to abandon Aleppo, and so the negotiations broke down (presumably quite to the relief of Saladin's allies in Mesopotamia). Saladin was now prepared to carry out a long siege of Mosul, but the Caliph's representative convinced him to lift the siege.
Saladin took his army west to Sinjar. After a two-week long siege the city fell, and was sacked by Saladin's army. 'Izz ad-Din had to respond to this threat to his power, and led his army west to confront Saladin. Once again negotiations began and once again they collapsed over Aleppo. 'Izz ad-Din was unwilling to risk a battle and withdrew to Mosul, a great blow to his prestige.
Saladin had failed in his attempts to gain the Caliph's support at Mosul, but his efforts did result in the grant of a diploma granting him sovereignty over Diyar Bakr, the area on the upper reaches of the Tigris (including Hisn Kaifa). Saladin moved into Diyar Bakr and began a three-week long siege of Amid, the main city in the area. The city fell, and was granted to Nur ad-Din Mohammad, the ruler of Hisn Kaifa. Saladin's secretary was allowed to take books from the library, which was large enough to more than fill a convoy of seventy camels. After his success as Amid the cities of Mayyafarqin (in the north of Diyar Bakr) and Mardin (south of Amid) both submitted to Saladim.
Saladin's next target was Aleppo, where 'Imad ad-Din was beginning to feel rather vulnerable. Saladin arrived outside Aleppo on 21 May 1183, and began a siege. At first the defenders seem to have had the better of the fighting, making a number of sorties that inflicted significant losses on Saladin's forces. Amongst the dead was his youngest brother Taj-al-Mulk Bori. The siege was eventually decided by 'Imad ad-Din's lack of money and determination. 'Imad ad-Din felt isolated at Aleppo, and his brother's actions in stripping the treasury and armoury had weakened his position. He decided to open negotiations with Saladin, who offered him Sinjar, Nisibin, Saruj and ar-Raqqa. This was too good an offer for 'Imad ad-Din to refuse, and on 11 June Saladin took control of the citadel. After a tense initial meeting Sadalin's generosity won over the garrison and defenders of Aleppo, who had feared the worst.
Saladin now controlled most of Nur ad-Din's empire. Only Mosul remained outside his control. During the rest of 1183 and 1184 Saladin was distracted by the need to secure his control of his own empire and by a series of minor campaigns against the Crusaders, but early in 1185 a four year long truce was agreed between Saladin and the Crusaders, leaving him free to turn his attention to Mosul.
While Saladin had been engaged in Syria, 'Izz al-Din had been looking to the east. He formed an alliance with Pahlavan, the Seljuk Atabeg of Azerbaijan and parts of Persia. The new allies threatened the lord of Irbil, who was himself an ally of Saladin. Saladin crossed the upper Euphrates and moved east towards Mosul, gathering allies as he went. 'Izz ad-Din's own allies didn't move, although the Seljuk Sultan of Konya (the Sultanate of Run in Anatolia) did threaten to intervene.
Saladin's army arrived outside Mosul in July 1185 and besieged the city. This siege would be disrupted twice, first by a threat to the north and then by illness. Pahlavan caused the first disruption with a threat to take Akhlat, a fortress on the western shores of Lake Van. Baktimore, the new ruler of Akhlat, asked for Saladin's assistance and a few weeks after beginning the siege most of Saladin's army moved away to the north. The expedition ended in failure, when Baktimore made peace with Pahlavan and married one of his daughters. Saladin and his troops returned to Mosul, only for illness to intervene. Saladin fell sick, and on 25 December was forced to lift the siege.
While Saladin was ill he discovered that his power wasn't quite a secure as he had hoped. His cousin Nasir-ad-Din, governor of Homs, gathered support for his claim to succeed Saladin, while his nephew Taqi-ad-Din, was showing signs of ambition in Egypt. Their plots came to nothing after Saladin recovered from his illness, but they may have played a part in finally allowing for a compromise between Saladin and 'Izz ad-Din. In February 'Izz ad-Din sent an embassy to Saladin, and on 3 March 1186 the two ruler's ambassadors signed a peace treaty. 'Izz ad-Din remained as ruler of Mosul but he lost control of the area south of Mosul, acknowledged Saladin as his overlord and agreed to provide troops for the Holy War. Two days later Nasir-ad-Din died, and Saladin's position in his newly expanded empire was safe.
In the spring of 1186 Saladin was thus in a strong position. He ruled Egypt, controlled Aleppo, Damascus and Mosul, and had the support of the Caliph in Baghdad. The Crusader Kingdoms were now in a very vulnerable position, facing the same hostile power along their southern and eastern borders. They were protected by a four year truce with Saladin, of which three were still to run, but this temporary respite would be thrown away by Raynald of Chatillon, ruler of al-Karak. He refused to accept the truce, attacked a caravan heading past his territory and then refused to make reparations. This gave Saladin the excuse he needed to end the truce, and in 1187 Saladin launched the campaign that would reach its climax with his crushing victory at the battle of the Horns of Hattin on 4 July 1187.