European military expeditions into Palestine between 1095 and 1270.
The first centuries of the Holy Roman Empire were characterized by increasing wealth of the aristocracy from the growth in commercial activity and by religious control over every aspect of life. The wealthy combined pleasure and religious duty by going on pilgrimages to the "Holy Land." Palestine was under Muslim control at the time, which made access to holy places often difficult.
As the Muslim pressure on the southern borders of the Eastern (Byzantine) Empire and its capital Constantinople grew, emperor Alexius I Comnenus turned to the pope for help. At a church council meeting in 1095 Pope Urban II called on all European sovereigns to raise an army and liberate the Holy Land. His call gave rise to a series of crusades, commonly counted as eight:
| 1st crusade | 1096 - 1099 | |
| 2nd crusade | 1147 - 1149 | |
| 3rd crusade | 1189 - 1191 | |
| 4th crusade | 1202 - 1204 | |
| 5th crusade | 1218 - 1221 | |
| 6th crusade | 1228 - 1229 | |
| 7th crusade | 1248 - 1250 | |
| 8th crusade | 1270 |
Following Pope Urban's call several knights, assisted by less organized bands and adventurers, assembled troops in Constantinople. In 1098 a long siege led to the fall of Antioch, where the crusaders established a Christian principality. Jerusalem fell in 1099, and the kingdom of Jerusalem was established after its Muslim and Jewish inhabitants had been slaughtered. Two more crusader states, the county of Tripoli and the county of Edessa, were established in the same year.
When Edessa returned to Muslim control in 1144, Pope Eugenius III called for another crusade. It was led by Emperor Conrad III of Germany and King Louis VII of France. Their two armies met in Jerusalem and marched towards Damascus. They were forced into retreat, and the second crusade did not achieve anything.
In the years between the second and third crusade the Muslim Seljuq empire expanded and encircled the crusader states. In 1187 the Seljuq army defeated Jerusalem's army and captured the city and most other crusader outposts.
Determined to recapture Jerusalem, Pope Gregory VIII called for a third crusade. The crusader army, the largest so far, was under the command of Emperor Frederick Barbarossa, who drowned on the way. Under the command of Richard I the Lion-Heart of England the troops met with those of Phillip II Augustus of France. They took Cyprus from the Byzantine Empire and Acre from Muslim control but did not reach Jerusalem. The crusade ended with a five year peace treaty that allowed Christian pilgrims to access the holy places.
In 1198 Pope Innocent III called for yet another crusade, this time to get a foothold in Egypt. But the crusaders were unable to pay the City of Venice for the ships to transport the troops and had to assist Venice with the capture of a Hungarian city first. They then took the opportunity to capture and sack Constantinople in 1204 and establish the short-lived "Latin Empire of Constantinople." Although Pope Innocent came out strongly against this adventurism, the fourth crusade was the definite end of any collaboration between the Byzantine Empire and the pope.
The years between the fourth and fifth crusade witnessed the Children's Crusade of 1212, a movement of religious fervour that assembled more than 30,000 children in Marseille with the aim of conquering the Holy Land through love, not war. Some merchants smelled hefty profit and shipped the children to North Africa, where they sold them into slavery. A group of 20,000 German children crossed the Alps and eventually dispersed throughout Italy, where they were captured and sold individually as slaves.
This crusade was again called by Innocent III and directed against Egypt. It was the last crusade to be called by a pope. The crusaders captured Damietta near the Nile but were unable to reach Cairo because of floods and had to accept an eight year truce.
This crusade was organized by Emperor Frederick II of Germany. Although the pope did not directly call for it, he had a clear interest in it: He authorized the usual church levy to finance it and excommunicated Frederick because the emperor found too many excuses to delay its departure. Eventually Frederick managed to negotiate the return of Jerusalem to Christian control in 1229.
Jerusalem had again fallen to Muslim control in 1244, and King Louis IX of France launched another crusade. Again an attempt was made to proceed via Egypt; again Damietta was taken, but the crusader army was trapped in Cairo and decimated.
Louis' final attempt at a successful crusade in 1270 ended before it began. The crusaders were shipped to Tunis, where the king and his troops fell ill and died.
The remaining crusader states were captured during the years that followed and their inhabitants slaughtered. Antioch fell in 1268, Tripoli in 1289 and Acre in 1291.