Military history of the Crusader states
The Seljuk–Crusader War began when the First Crusade wrested territory from the Seljuk Turks during the Siege of Nicaea in 1097 and lasted until 1128 when Zengi became atabeg of Aleppo. At the latter date, the chief threat to the Crusaders from the east and north became the Zengids. The conflict was generally fought between European Crusaders and the Seljuk Turks and their vassals. The Muslim Syrian emirates occasionally allied themselves with the Christians against rival states.
Persecution of Muslims
The coming of the Crusades (starting with the massacre of Barbastro) and similarly entrenched positions on the northern African Almoravids, who took over al-Andalus as of 1086, added to the difficult coexistence between communities, including Muslims in Christian ruled territory, or the Mozarabic rite Christians (quite different from those of the northern kingdoms), and further minority groups. The Almohads, a fanatic north African sect, pushed the boundaries of religious intolerance during their occupation of al-Andalus, affecting also the Jews.
During the expansion south of the northern Christian kingdoms, depending on the local capitulations, local Muslims were allowed to remain (Mudéjars) with some restrictions, while some were assimilated into the Christian faith. After the conquest of Granada, all the Spanish Muslims were under Christian rule. The new acquired population spoke Arabic or Mozarabic, and the campaigns to convert them were unsuccessful. Legislation was gradually introduced to remove Islam, culminating with the Muslims being forced to convert to Catholicism by the Spanish Inquisition. They were known as Moriscos and considered New Christians. Further laws were introduced, as on 25 May 1566, stipulating that they 'had to abandon the use of Arabic, change their costumes, that their doors must remain open every Friday, and other feast days, and that their baths, public and private, to be torn down.' The reason doors were to be left open so as to determine whether they secretly observed any Islamic festivals. King Philip II of Spain ordered the destruction of all public baths on the grounds of them being relics of infidelity, notorious for their use by Muslims performing their purification rites. The possession of books or papers in Arabic was near concrete proof of disobedience with severe repercussions. On 1 January 1568, Christian priests were ordered to take all Morisco children between the ages of three and fifteen, and place them in schools, where they should learn Castillian and Christian doctrine. All these laws and measures required force to be implemented, and from much earlier.