The Second Crusade, Chapter 1: The Fall of Edessa and a New Crisis

Following the First Crusade, Crusader states, including the Kingdom of Jerusalem, were established, but they continuously clashed with surrounding Islamic forces. The County of Edessa in the north, in particular, was in a more difficult position to defend than other Crusader states. In the mid-12th century, Zengi, who had seized Mosul and Aleppo, was expanding his influence within the Islamic world. In December 1144, Zengi attacked Edessa, breached the Crusader defenses, and captured the city. The fall of Edessa sent a major shockwave through the Crusader states. As Edessa was the first Crusader state established after the First Crusade, its loss meant more than just losing a single city. Jerusalem's defenses against attacks from the north also became vulnerable. Amidst this crisis, calls for a new crusade grew louder in Europe. This became the direct catalyst for the start of the Second Crusade.