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.
Military history of the Crusader states
The war with Fatimid Egypt began when the First Crusade invaded Fatimid territory and started the Siege of Jerusalem in 1099. Soon after, the Crusaders stormed and captured the city. The war between the newly established Latin Kingdom of Jerusalem and Fatimid Egypt continued until Saladin became the effective ruler of Egypt in 1169.