In 1125 he participated in the Battle of Azaz, a Crusader victory against the atabeg of Mosul.
In 1131, during the siege of a small castle north-east of Aleppo, a sapper's mine collapsed and Joscelin was gravely injured. Shortly thereafter, he recived word that emir Ghazi of Danishment was marching against the fortress town of Kaisun. When Joscelin's own son refused to aid the town, he commanded that his own army should decamp and Joscelin was borne on a litter before the army. When Ghazi heard of Joscelin's approach, perhaps mistakenly believing him already dead, he lifted the siege and retreated, and thus the warrior prince won a final battle before dying shortly thereafter on the roadside.
References
Preceded by:
Baldwin II
County of Edessa
Followed by:
Joscelin II