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.
Sigurd the Crusader
In 1107, Sigurd led the Norwegian Crusade to support the newly established Kingdom of Jerusalem which had been founded after the First Crusade. He was the first European king to lead a crusade, and his feats earned him the nickname "Jorsalafari". Sigurd possessed a total force of about 5000 men in about 60 ships, as recorded by the sagas. The two kings, Øystein and Sigurd, initially disputed about who should lead the contingent and who should remain home to rule the kingdom. Sigurd was eventually chosen to lead the crusade, possibly because he was a more experienced traveler, having been on several expeditions with his father, Magnus III, to Ireland and islands outside Scotland.