The Battle of Hattin (also known as the Battle of the Horns of Hattin for the twin peaks of a nearby volcano) was fought between the Kingdom of Jerusalem under Guy of Lusignan and the Ayyubid Sultanate under Salāḥ ad-Dīn from 3 to 4 July 1187.
As the Saracens, recently resupplied by the merchant Tamir, besieged the fortress at Tiberias, Guy and his forces marched to relieve Raymond III of Tripoli. Guy however, made a grave error by attempting to force his way through the Saracen army, leaving behind his only source of fresh water in the process.
Unable to advance or pull back, the thirsty crusaders were forced to camp in the middle of the searing plain. The saracens surrounding them fired constant volleys of arrows at them and set fire to the grass to further dehydrate their enemies. Each attempt to break out failed, and Salāḥ ad-Dīn's forces drove the crusaders up into the Horns where they were decimated.
The crusaders surrendered, and Guy was taken prisoner by Salāḥ ad-Dīn along with Raynald of Châtillon and Gerard de Ridefort, Grand Master of the Templar Order. Salāḥ ad-Dīn then executed Raynald and several Templars and Hospitaliers. Following the battle, the Saracens retook all of the cities previously conquered by the crusaders, except for Tyre and Antioch. With news of the disastrous defeats and the fall of the Kingdom of Jerusalem, the Third Crusade was launched two years later.