During this time conflict with the Crusader states was also intermittent, and after the First Crusade increasingly independent atabegs would frequently ally with the Crusader states against other atabegs as they vied with each other for territory. At Mosul, Zengi succeeded Kerbogha as atabeg and successfully began the process of consolidating the atabegs of Syria. In 1144 Zengi captured Edessa, as the County of Edessa had allied itself with the Artuqids against him. This event triggered the launch of the Second Crusade. Nur ad-Din, one of Zengi's sons who succeeded him as atabeg of Aleppo, created an alliance in the region to oppose the Second Crusade, which landed in 1147.