Crusades, under papal authority, wars waged in the Middle Ages (11th–13th centuries) by European Christians against the Muslims to recover the Holy Land, particularly Jerusalem. The initial impetus for the Crusades was a revival of religious fervor, as urged by Pope Urban II at the Council of Clermont (1095); however, conquest of territory, the attraction of riches, and the possibility of expanded trade with the East were also vital elements. At the end of the First Crusade (1095–99) Jerusalem was retaken and the Latin kingdom of Jerusalem was established, as were the orders of the Knights Templars and the Knights Hospitalers. The Second Crusade (1147–49), a response to the loss of Edessa (1144) to the Turks, ended in failure. The Third Crusade was an attempt to recapture Jerusalem, lost to Saladin in 1187. Holy Roman Emperor Frederick I, Richard I of England, and Philip II of France led this crusade, but were only able to achieve a 3-year truce that gave Christians access to the holy city. During the Fourth Crusade (1202–4) the Crusaders seized Constantinople. In 1212 the tragic Children's Crusade was waged. Thousands of children died of hunger or disease or were sold into slavery as they headed toward the Holy Land. The goal of the Fifth Crusade, another failure, was Egypt. There was a Sixth Crusade (1228–29) in which another short-lived truce was arranged with the Muslims, and then 3 additional crusades, but Muslim gains held steady. The last Christian stronghold, Akko (Acre), fell in 1291.