The Crusades were a series of wars taking place in Asia Minor and the Levant between 1095 and 1291, in which Western European nations engaged using the propaganda of religious expeditionary wars. The first crusade was called by Pope Urban II of the Roman Catholic Church, with the stated goal of restoring Christian access to the holy places in and near Jerusalem. The background to the Crusades was the centuries of Arab–Byzantine Wars and the Seljuq-Byzantine Wars and the recent decisive defeat of the Byzantine army by Seljuk Turks at Manzikert in 1071. The Norman conqueror Robert Guiscard's conquest of Byzantine territories added to the problems of the Byzantine Empire. In an attempt to curtail both dangers, its Emperor Alexios I sought to align Christian nations against a common enemy, requested western aid, and Pope Urban II in turn enlisted western leaders in the cause of taking back the Holy Land.
Krak des Chevaliers (French pronunciation: [kʁak de ʃəvaˈlje]) (Arabic: قلعة الحصن), also Crac des Chevaliers, is a Crusader castle in Syria and one of the most important preserved medieval castles in the world. The site was first inhabited in the 11th century by a settlement of Kurds; as a result it was known as Hisn al Akrad, meaning the "Castle of the Kurds". In 1142 it was given by Raymond II, Count of Tripoli, to the Knights Hospitaller. It remained in their possession until it fell in 1271. It became known as Crac de l'Ospital; the name Krak des Chevaliers was coined in the 19th century.
The Hospitallers began rebuilding the castle in the 1140s and were finished by 1170 when an earthquake damaged the castle. The order controlled a number of castles along the border of the County of Tripoli, a state founded after the First Crusade. Krak des Chevaliers was amongst the most important and acted as a centre of administration as well as a military base. After a second phase of building was undertaken in the 13th century, Krak des Chevaliers became a concentric castle. This phase created the outer wall and gave the castle its current appearance. The first half of the century has been described as Krak des Chevaliers' "golden age". At its peak, Krak des Chevaliers housed a garrison of around 2,000. Such a large garrison allowed the Hospitallers to extract tribute from a wide area. From the 1250s the fortunes of the Knights Hospitaller took a turn for the worse and in 1271 Krak des Chevaliers was captured by the Mamluk Sultan Baibars after a siege lasting 36 days, and then purportedly only by way of a forged letter purportedly from the Hospitallers' Grand Master that caused the Knights to surrender.