@STNGfan,
FIRST CRUSADE (1095-9): Proclaimed by Pope Urban II, motivated by the Turkish occupation of Anatolia and Jerusalem about 50 years earlier, which was interfering with Christian pilgrimages, and had spawned tales of heathens brutalizing and massacring Christian subjects in the East. The Crusaders captured Jerusalem and established several Latin kingdoms. Despite several missteps (like killing communities of Christians by accident, and the Peasants' Crusade, which didn't know where it was going and tended to kill everything in its path), this was the most successful Crusade.
SECOND CRUSADE (1147-9): Led by Louis 7th of France and the Holy Roman Emperor, this Crusade was a disaster.
THIRD CRUSADE (1189-92): Mounted to recapture Jerusalem, which had been retaken in 1187 by Saladin, who would become known as the Islamic forces' greatest general. A personal rivalry between the leaders, Phillip II of France and Richard I of England, undermined this one.
FOURTH CRUSADE (1202-4): This Crusade was initially launched against Egypt, which was in Islamic hands, but it was diverted by the Venetian merchants (who owned the ships the Crusaders were traveling on) to attack Christian Constantinople, a commercial rival of theirs. The Crusaders sacked the city and killed untold of its citizens. This attack permanently weakened the Byzantine Empire, even though the Byzantines retook their capital after 50 years of a weak Latin-backed puppet state.
CHILDREN'S CRUSADE: The Peasants' Crusade would probably have been the worst idea of the whole period except for this one: thousands of children were sent off by themselves across Europe, unarmed, on a divinely inspired mission — it was believed only innocents could retake the Holy Land. The ones that didn't die of disease or hunger along the way were sold into slavery by the flabbergasted Muslims when they got there.
FIFTH CRUSADE (1218-21): Took, then lost, Egypt.
SIXTH CRUSADE (1228-9): Led by the Holy Roman Emperor, Frederick II (R. 121-1250). It recovered Jerusalem through negotiations with the sultan of Egypt. The city was lost again in 1244.
SEVENTH CRUSADE (1249-54) and EIGHT CRUSADE (1270-91): Both were led by Louis 9th of France (R. 1226-70) who was inspired by religious visions. Both were disasters, but Louis was later canonized.
EFFECTS OF THE CRUSADES
The overall effects of the Crusades were mixed: they never permanently took Jerusalem, and the results of the Fourth Crusade actually strengthened the Islamic forces by weakening the Byzantine Empire, which had up till this point been able to hold them at bay. While the Byzantines regained their capital 50 years later, the Byzantine Empire after the Fourth Crusade was only a shadow of its former self.
More positive effects of the Crusades were felt by the Western Europeans: the extensive travel of the Crusades, which for most was their first time they had gone outside their own homelands, opened the eyes of Western Europeans to the broader world. Exotic goods like Eastern spices that the Crusaders had become exposed to (sometimes through pillaging) created new desires in the West, and encouraged the growth of long-distance trade. The Crusades also helped reintroduce the West to their own literary heritage from Classical Greece and Rome, which had been far more extensively preserved by the Byzantines and even by the Muslims (books were also pillaged, and later translated). The Crusades in the long run helped lead to the revival of classical learning in the Renaissance.
On the more negative scale, the Crusades helped bring in a more militantly aggressive ethos into Christianity, and the pogroms against the Jews which were begun in the Crusades continued throughout the High Middle Ages and into the modern period. The attitudes which the Crusaders had shown toward Jews and Muslims in the Crusades would be repeated in the Christian reconquest of Spain in the 1400s.
[illustration: Medieval illustration of Peter the Hermit leading Peasants' Crusade]