1. Beginning of the Crusades
Request from Byzantine emperor: A Byzantine emperor asked Pope Urban II for help against Muslim Seljuk Turks, who had beaten them at the battle of Manzikert and then overrun Byzantine territory in Asia Minor. In 1095, Urban responded by calling on European Christians to join in a war to free the Holy Land from Muslim control.
Different motivations: Many warriors of Western Europe became crusaders out of religious fervor; others sought adventure and wealth. Still others saw an opportunity for engaging in trade.

2. Progress of the First Crusade: Although the Byzantines began to have second thoughts about the possible actions of the crusaders, a large army of warriors succeeded in capturing Antioch in 1098 and then moved down the coast of Palestine toward Jerusalem.

3. Crusader Conquests and Losses
Capture of Jerusalem and formation of crusader states: In 1099, Christian warriors captured Jerusalem. By the 1140s, however, Muslim forces began to strike back, regaining territory taken by Christians. Saladin, the sultan of Egypt, later gained command of the Muslim armies and made them stronger.

4. Crusader Conquests and Losses
Dependence on Italian ports: Italian port cities served as the only source of supplies for the crusader kingdoms. Some of these cities— such as Genoa, Pisa, and Venice—grew wealthy and powerful from the trade.
Loss of Jerusalem to Saladin: Although a Second Crusade was launched to support the crusader kingdoms, Saladin retook Jerusalem in The Third Crusade failed to wrest the city from Muslim control, but Saladin agreed to allow Christian pilgrims to visit Jerusalem

5. The Later Crusades
Fourth Crusade: During the Fourth Crusade, the crusading army became involved in a fight for the Byzantine throne. The crusaders sacked Constantinople, permanently weakening the Byzantine Empire and widening the rift between the Eastern Orthodox Church and the Catholic Church.
Other Crusades: Later Crusades had little success. Participants in the Children's Crusade of 1212 failed to get anywhere near the Holy Land, with many shipwrecked or sold into slavery, and two Crusades led by King Louis IX of France failed to conquer any Muslim territory

6. Impact of the Crusades
Persecution of Jews: One effect of the Crusades was the first extensive attacks against Jews in Europe, who were viewed by some fanatics as greater enemies to Christianity than the Muslims were.
Breakdown of feudalism: Feudalism was weakened as a result of the Crusades. Nobles who joined or financed the Crusades often sold their land and freed their serfs. The resulting loss of the nobles' power allowed kings to create stronger central governments, paving the way for the rise of powerful nation-states.