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.
Medieval II: Total War: Kingdoms
Beginning in 1174, the Crusades Campaign is set several years prior to the outbreak of the Third Crusade, continuing into the Fourth Crusade and beyond. It follows the Kingdom of Jerusalem led by Richard the Lionheart and the Principality of Antioch led by Philip Augustus as they attempt to strengthen the presence of Christendom in the Holy Lands, whilst the Zengid Emirate led by Nur ad-Din Zangi and the Ayyubid Sultanate led by Saladin attempt to drive them out. Meanwhile, the Byzantine Empire led by Emperor Manuel Komnenos slowly moves into the middle east to regain its lost glory, and attempts to drive back the armies of the Turks as well as deal with the rebels and the Venetians that harass them in the west.Generals in the Crusades campaign have the ability to construct permanent forts that remain even after vacated by troops.