The fall of Edessa to Imad ad-Din Zengi was a crucial moment in the history of the Crusades. As the atabeg of Mosul and Aleppo, Zengi sought to consolidate power and resist the encroachment of the Crusader states established during the First Crusade. Edessa, founded in 1098, became one of the first Crusader states and represented a significant foothold for Western powers in the East. Its strategic location allowed control over trade routes and religious pilgrimage paths.

During the siege, which began in late 1144, Zengi utilized effective siege tactics, including the use of siege engines to breach the city walls. After a prolonged period of resistance, the defenders eventually surrendered on December 24, 1144. This victory not only boosted the morale of Muslim forces but also served to galvanize opposition against the Crusader states in the region.

The capture of Edessa had broader implications for the Crusader states, signaling a shift in the balance of power. It forced the Western powers to reconsider their strategies in the Holy Land, leading to calls for a Second Crusade, aimed at recapturing lost territories. The fall of Edessa also instigated fear among other Crusader forces, as it demonstrated the growing strength and organization of Muslim leaders like Zengi.