Joscelin of Courtenay or Joscelin I ruled over the County of Edessa during its zenith, from 1118 to 1131. He maintained the large and unstable borders through his martial prowess. He arrived in the Holy Land during the Crusade of 1101 after the First Crusade.
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 received word that emirGhazi of Danishmend 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
Runciman, Steven. A History of the Crusades: Vols. I-II. Cambridge University Press 1951
Joscelin II inherited Edessa and Turbessel in 1131 on the death of his father, and desperately tried to defend his extensive borders against his hostile Muslim neighbours.