Stimulated by Pope Innocent III, whose tenure of that high office marked the apex of the medieval papacy. The Crusaders were originally bound for Egypt, but were persuaded by Alexius, son of Isaac Angelus, the dispossessed Emperor of Byzantium, to turn aside to Constantinople in order to restore him and his son to the throne. The story of the fourth crusade might well be told with tears of humiliation for the disgrace which it was to Christendom.
A motley collection of French knights setting out from Venice by sea to fight in the Holy Land, the crusaders appealed to the Venetians for transportation and food. Venice held extensive commercial interests in the eastern Mediterranean and wished an eastern emperor who would be compliant and supported a candidate for post. This was only carrying to its logical conclusion the policy that the crusading royalty and nobility had followed all along, to carve out for themselves domains and principalities in the East. The merchants of Venice agreed to furnish at a high price, more than the crusaders could pay, and also to contribute 50 armed warships if they could share equally in all future conquests. The Duke of Venice, the blind Enrico Dandoelo, used the indebtedness to use the crusaders to his own political ends. They were to capture for Venice, the port of Zara, who had revolted against Venice and had gone over to the king of Hungary. Venice was now quarreling with Constantinople, and the Crusaders consented to begin their expedition with an attack on their fellow Christians. There was no great Bernard to inspire enthusiasm, but a preacher of a distinctly lower type, Fulco of Neuilly, succeeded in obtaining support from a number of French nobles, who involved themselves in the unworthy obligations to blind Dandolo. So the crusade began with the sack and destruction of a Roman Catholic town, in 1202. Angrily, the pope had excommunicated the crusaders. Pope Innocent was infuriated by this bargain which had diverted them from such a noble cause and excommunicated the Crusaders...
This departure from their original design was followed by a still more remarkable deviation. Instead of proceeding to Palestine, they sailed against Constantinople, to dethrone the usurper, Alexius Angelus. The crusaders succeeded in restoring the lawful emperor, Isaac, to his Empire. The reward which they required was extravagant, and Isaac’s efforts to comply with the stipulations provoked such resentment, that he was deposed by his subjects, and put to death, together with his son. But worse was to follow. In July, 1203, the Crusaders took Constantinople by assault. The bulk of the fourth Crusade never reached the Holy Land at all. It started at Venice (1202), captured Zara, encamped at Constantinople (1203), and finally, in 1204, stormed the city. After an easy siege the gates were thrown open, and the Latins entered the city in triumph. The city was sacked. Naturally the pope protested at this second diversion of the crusading army «Ye took not the Cross to avenge the wrongs of the prince Alexius,» he wrote. «Ye are under the solemn obligation to avenge the Crucified, to Whose service ye are sworn.
They knew that Constantinople was a richer prize than all the Holy Land - and that it could be taken more easily. Constantinople had withstood Moslem armies for 5 centuries, it now fell. The imperial capital was stormed by the very men whose forefathers had promised rescue a century before. Untold treasures of gold, silver, and holy relics were plundered during the subsequent pillage and rape. Literary classics, great and wonderful works of art and treasures untold were either destroyed or carried away. Many of its priceless treasures were carried off to Europe. But the greatest prize of all were the relics. bones, heads and arms of saints. the crown of thorns, St. Thomas, the doubter's finger. The patriarch fled on an ass without a single attendant. Tombs were robbed. Women were outraged. Churches were desecrated. Horses were ridden in the sanctuary. Communion cups and sacred vessels were used as drinking cups in drunken revels. Prostitutes danced on the altar. Icons, even portraits of Christ were used as gaming tables.
The Byzantine emperor was murdered by his own people in a revolt. Venice took much of the coast and islands of the Empire, and the crusaders set up a Latin Empire with a Latin, Baldwin of Flanders as emperor. Pope Innocent II could express disapproval, but the Greeks were schismatics and heretics so their own rule was set up over the Greek Empire, which lasted 50 years. The Latin and Greek Churches were declared to be reunited, and Latin emperors ruled as conquerors in Constantinople from 1204 to 1261. This is the first time the Byzantine capital was taken, and a landmark in the history of relations between eastern and western Christians. Knights could now choose to crusade against the Greeks instead of the infidel Moslems.
Hated by the Greeks, deprived of help from home, driven out in 1261 by the Greek emperor of Nicaia, and the Byzantine Empire was restored. After this disaster it was entirely impossible to restore the Byzantine military or economic system, it became a mere shadow of its former self, now reduced to only a Balkan state. The Latin Empire of Constantinople is a complete freak of history. The Byzantine power was so shattered, it was now unable to check the Turkish sweep into Europe, and the hopes of uniting the eastern and western churches, which the possession of the Byzantine capital had inspired was blighted forever. The chief beneficiaries of this robbery were the Venetian who themselves took over the most lucrative parts of the former Empire, including Crete and the Aegean islands. Eastern Christendom has not forgotten those three appalling days of pillage. As the Byzantines watched the Crusaders tear to pieces the alter and icon screen of the Church of the Holy Wisdom, and set prostitutes on he Patriarch's throne, they must have felt that those who did such things were not Christians in the same sense as themselves.. The Crusaders did not bring peace, but a sword, and the sword was to sever Christendom to this day. Between the fall of Rome and the discovery of America the Fourth Crusade is the most important event in the history of European trade. It established the Venetian Empire.