The Second Crusade (1147–1149) was the second major crusade launched from Europe. The Second Crusade was started in response to the fall of the County of Edessa in 1144 to the forces of Zengi. The county had been founded during the First Crusade (1096–1099) by the future King Baldwin I of Jerusalem in 1098. While it was the first Crusader state to be founded, it was also the first to fall.
The Second Crusade was announced by Pope Eugene III, and was led in the east by European kings Louis VII of France and Conrad III of Germany, with help from a number of other European nobles. The armies of the two kings marched separately across Europe. After crossing Byzantine territory into Anatolia, both armies were separately defeated by the Seljuk Turks. The main Western Christian source, Odo of Deuil, and Syriac Christian sources claim that the Byzantine Emperor Manuel I Komnenos secretly hindered the crusaders' progress, particularly in Anatolia, where he is alleged to have deliberately ordered Turks to attack them. However, this alleged sabotage of the Crusade by the Byzantines was likely fabricated by Odo, who saw the Empire as an obstacle; moreover, Emperor Manuel had no political reason to do so. Louis and Conrad reached Jerusalem in 1148, where the remnants of their armies participated in an ill-advised attack on Damascus that ended in their retreat. Crusader efforts were successful in Iberia, where several territories—including Lisbon, the future capital of the Portuguese Empire—were conquered.