The capital of the crusader County of Edessa falls to Imad ad-Din Zengi, the atabeg of Mosul and Aleppo.

The Crusades were a series of religious wars initiated, supported, and at times directed by the Papacy during the Middle Ages. The most prominent of these were the campaigns to the Holy Land aimed at reclaiming Jerusalem and its surrounding territories from Muslim rule. Beginning with the First Crusade, which culminated in the capture of Jerusalem in 1099, these expeditions spanned centuries and became a central aspect of European political, religious, and military history.

The County of Edessa was a 12th-century Crusader state in Upper Mesopotamia. Its seat was the city of Edessa.

The siege of Edessa took place from 28 November to 24 December 1144, resulting in the fall of the capital of the County of Edessa to Zengi, the atabeg of Mosul and Aleppo. This event was the catalyst for the Second Crusade.

Imad al-Din Zengi, also romanized as Zangi, Zengui, Zenki, and Zanki, was a Turkoman atabeg of the Seljuk Empire, who ruled Mosul, Aleppo, Hama, and, later, Edessa. He was the namesake and founder of the Zengid dynasty of atabegs.

Atabeg, Atabek, or Atabey is a hereditary title of nobility of Turkic origin, indicating a governor of a nation or province who was subordinate to a monarch and charged with raising the crown prince. The first instance of the title's use was with early Seljuk Turks who bestowed it on the Persian vizier Nizam al-Mulk. It was later used in the Kingdom of Georgia, first within the Armeno-Georgian family of Mkhargrdzeli as a military title and then within the house of Jaqeli as princes of Samtskhe.