The battle took place in the Galilee near Tiberias in present day Israel. The battlefield, near the town of Hittin, had as its chief geographic feature a double hill (the "Horns of Hattin") beside a pass through the northern mountains between Tiberias and the road from Acre to the west. The Darb al-Hawarnah road, built by the Romans, served as the main east-west passage between the Jordan fords, the Sea of Galilee and the Mediterranean coast.
Saladin's final invasion was triggered by the actions of Reynald of Chatillon. Reynald had first arrived in the Holy Land with the Second Crusade, and had decided to stay and make his fortune in the east. His behaviour demonstrated one of the main problems facing the crusader states. The established crusader barons had realised that to survive they needed to live on peaceful terms with their Muslim neighbours for as long as possible. However, to maintain their numbers they needed to attract new crusaders from the west, and these new crusaders were much less willing to live peacefully with the infidels that they had come to fight. Reynald had had an eventful career in the east, and by 1187 he had been lord of Oultrejourdain, on the south eastern edge of the Kingdom of Jerusalem, for over a decade. From his base at Kerak he had repeated broken treaties with Saladin, attacking trade caravans, and once mounting a naval raid into the red sea, attacking the ports of Medina and Mecca. This outrage enraged Saladin, and triggered an unsuccessful invasion of the Kingdom of Jerusalem.
Horns of Hattin, as viewed from the east
Now, at the end of 1186, and with the Kingdom in desperate need of a few years of peace to restore order, Reynald committed another outrage. As a huge caravan travelling north from Cairo passed through Frankish lands, under the protection of treaty, Reynald launched an attack on it, killing the guards, stealing the trade goods, and taking the merchants hostage. Saladin first attempted to act within the terms of the treaty, and sent envoys demanding the return of the merchants and their goods, first to Reynald, who ignored them, and then on to King Guy, who listened to them and agreed that they were in the right. However, he was far too dependant of Reynald for his power, and could not take the risk of an attack on his main ally. The envoys returned unsatisfied, and war was now inevitable.
Once it was clear that war was looming, the weakness and dissention of the crusader states became apparent. Bohemond of Antioch renewed an already existing truce, while Raymond of Tripoli rushed to make a new one. Significantly, this truce was extended to cover this wife's principality of Galilee, actually part of the kingdom of Jerusalem. The true impact of this division came in April. King Guy summoned his allies and marched into Galilee, hoping to crush all resistance before Saladin could launch his invasion. However, at the same time Saladin's son decided to launch an armed reconnaissance into Palestine. Obeying the terms of their truce, he sent envoys to Raymond to ask for free passage, and with great embarrassment, Raymond had to agree. On 1 May, a force of 7000 mamluk cavalry marched into Galilee, where they encountered the a force of Knights Templers, who despite being hugely outnumbered charged to the attack, and were almost entirely wiped out, with only three escaping. News of this disaster finally healed the split between Raymond and Guy. Raymond renounced his treaty with Saladin, and submitted to Guy, who accepted him with good grace. In contrast to this chaos, Saladin had been carefully gathering together his army, eventually gathering a force of some 20,000 men, forming the largest army he had ever commanded. Despite their arguments, the crusaders were able to raise a force of almost the same size. At this point there was nothing to suggest that a disaster was about to occur. The crusaders had defeated similar invasions by refusing to risk battle and occupying well supplied positions, while their enemies armies wilted away in the sun. This had happened four years before, and Saladin had been forced to withdraw without battle.
Artistic representation of Saladin
On 1 July Saladin crossed the Jordan. He attacked Tiberias, capturing the town and besieging the castle. Despite strong advice to remain at Acre, Guy was persuaded to march inland towards Tiberias. Even then, not all was lost. On 2 July the crusaders camped at Sephoria, where they had a good water supply and the best of the terrain. Although most of the knights spoke for moving on, Raymond of Tripoli himself, whose wife was defending Tiberias was strongly against such a move, arguing that Saladin would not be able to attack their position, while reinforcements from Antioch were expected, and when the council ended it appeared that he had won the day. Sadly for the crusader cause, Guy was easy to persuade, and after the council broke up the Grand Master of the Temple managed to change his mind. The next day the crusaders marched east along a barren, waterless road, under constant harassment by Saladin's skirmishers, and the crusaders soon suffered from thirst. By mid afternoon the crusaders reached the horns of Hattin, a barren hill top overlooking the village. Despite urgent calls to fight to the lake that afternoon, Guy decided to halt the march. This move has been criticised, but it is likely that the army was too drained to risk a fight. Moreover, the eventual campsite did have a well, and was probably picked for this. Unfortunately, the well was dry. While Saladin and his army spend the night in the well watered valley, the crusaders spent the night in misery on the dry hill top.
The battle itself was now something of a foregone conclusion. At dawn on 4 July, the crusader army found itself surround on the hill top. In normal circumstances this move would have been a mistake for Saladin, as the crusader army was quite close to his in numbers, and would have been able to punch a hole in the weakened Muslim cordon, but after a day and a night without water the crusader army had lost much of it's cohesion. The infantry broke from the army and made a desperate attempt to reach water, but failed, and were soon destroyed. The crusader cause was now doomed. The trapped knights fought with great determination, but were steadily forced back towards the summit. An attempt to force a breakthrough led by Raymond of Tripoli was foiled when Saladin's army simply opened a gap to let them through. Stuck on the outside of the battle there was nothing they could do, and so they escaped back to Tripoli. Those left on the hill fought to exhaustion, but eventually were forced to surrender. Saladin's triumph appeared to be complete. He had captured King Guy, along with Reynald of Chatillon and most of the great barons of the Kingdom, as well as capturing the Holy Cross. The prisoners were all well treated, apart from Reynald of Chatillon, whose foolish raids had led to the defeat, and for whole Saladin felt such hatred that he personally beheaded him.
The Battle of Hattin, from a medieval manuscript Defeat at Hattin saw the effective destruction of the Kingdom of Jerusalem. With the King in his hands, and the army destroyed, Saladin was able to capture city after city. Tiberias surrendered quickly, Acre on 10 June and finally on 2 October, Jerusalem itself surrendered.