The Second Crusade was an attempt to stop Muslims from taking key land from Christians during the years from 1147 to 1149. The attempt was started by Pope Eugene III, but the armies failed in the attempt to stop Muslim control completely. Part of the reason is that many of the fighting knights had been killed during the first Crusades, leaving fewer fighting soldiers to take part.
The Second Crusade was initiated because the County of Odessa had been captured in 1144. The first attack by the Crusaders was on Damascus, where they were defeated by the Turks. It is believed that there was a lack of communication between the kings who were fighting the battle together. As a result of this, two different targets were attacked simultaneously. Instead of one large army conquering one area at a time, the split caused both armies to fail.
The failed Second Crusade caused economic trouble in Europe. Additionally, Egypt and Syria became united against the Christians. Because the countries were united, the Crusaders were surrounded and Jerusalem was left without adequate protection. Some believe that an unprotected Jerusalem led to the outcry for the Third Crusade. Although the Second Crusade failed, the armies did acquire Lisbon and other smaller cities.