"Crusade" means "going to the cross." These wars of the Middle Ages were an effort by Christendom to reclaim the Holy Land from Muslim forces who controlled the territory. Begun by Pope Urban II in 1045, there were four in sum:
The First Crusade (1045): This Crusade was a success for the Christian Armies as they gained the key city of Jerusalem.
The Second Crusade (1145): This Crusade is considered a failure. The Crusaders from France and Germany were unable to take the city of Damascus. Eventually Jerusalem would fall back into Muslim control.
The Third Crusade (1189): This Crusade features two of the most famous figures of the era: Richard the Lionheart from England, and the Muslim leader Saladin. This Crusade had marginal success, and some hearty failures. The Holy Roman Emperor, Frederik Barbarossa, drowned on the journey so most of the German soldiers turned around and went home. This Crusade saw the Christian Armies take the cities of Acre and Jaffa, but failed to re-capture Jerusalem. A compromise with Saladin allowed unarmed Christian Pilgrims to visit the city of Jerusalem.
The Fourth Crusade (1202): The failure of the Third Crusade to take Jerusalem prompted the Fourth Crusade. This Crusade featured a diversion to sack the city Constantinople, sealing the split between the Eastern and Western Churches.
Another event called the Children’s Crusade in 1212 failed to conquer territory and resulted in thousands of children dying or being sold into slavery.
There were subsequent, minor Crusades after this, but none were successful. In sum, the goal of the Crusades, being to take the Holy Land from the Muslims, was a failure. The last stronghold of Christianity in the region fell in 1212.
The seeds for the First Crusade were sown with the destruction of the Church of the Holy Sepulchre in 1009 C.E. It occurred under the reign of the Fatimid (Shite) Caliph Abu Ali Mansur al-Hakim (996-1021 dates of reign). The edict for the destruction of the church was signed by al-Hakim's Christian secretary, Ibn Abdun. The church had been a pilgrimage destination for thousands of Europeans. With the urging of the Byzantine Emperor Alexius Commenus, in 1095 Pope Urban II repeatedly called for the capturing of the Holy Sepulchre from whom he called "a wicked race." His most powerful speech was made at Clermont in southeastern France. By the spring of 1096 a hundred and fifty thousand men, mostly Franks and Normans had answered the call. A number of the Crusaders had ulterior motives. Bohemond and others were intent on acquiring land. The merchants of Pisa, Venice and Genoa had commercial desires, The masses of France, Lorraine, Italy and Sicily were also inspired by financial gain.
The first Crusade started from Constantinople. In 1098 Edessa, then Tarsus, Antioch and Aleppo fell to the Crusaders. Jerusalem fell to the crusaders on July 15, 1099. The Crusaders massacrd men, women and children. The designation of the number of crusades is arbitrary--some say seven to nine. The beginning of one and end of another is blurred because there was a steady stream of invaders. It could be divided into three periods. The first one was a period of conquest ending in 1144. The second period was Muslim response to the Crusaders ending with Salahuddin (Saladin) who died in 1193. The third period was characterized by internal disputes between the Crusaders and ended in 1291. The crusades ended in 1291 under the leadership of the Mamluk sultans Baybars and his son al-Ashraf Khalil (1290-1293). The land that was occupied by the Crusaders was lost. Some of the Crusaders were able to hold onto their estates until their death. But in the end, the Crusaders were driven into the sea and the spiritual and financial goals of the Crusaders as a whole were lost. In the eyes of Christians, the pure of heart were martyrs and bound for heaven. In the eyes of Muslims, they were denizens of hell.