The Fourth Crusade: 1202–1204

The Fourth Crusade is, depending on whom you ask, the most tragic episode in the history of the Crusades, the most revealing, or both. It is the moment when the Western Christian armies did what no Muslim army had managed: they sacked Constantinople, the largest and richest city in Christendom, the capital of an Eastern Christian empire that had been an ally of the West in 1096. The events of 1204 have shaped Greek–Latin relations, the European imagination, and the historical profession ever since.

This pillar tells the story of the expedition, with a particular eye to how it went so badly wrong. For the broader story, see the main article on the Crusades and the causes of the Crusades. For the events leading up to the Sack, see why the Fourth Crusade sacked Constantinople and the role of Venice.

A note on the historiography, which is unusually contested. Three positions dominate. The traditional view, going back to Edward Gibbon and continuing through Steven Runciman’s History of the Crusades, is that the diversion was the result of Venetian greed. The position associated with Thomas Madden’s Enrico Dandolo and the Rise of Venice (2003) and Jonathan Phillips’s The Fourth Crusade and the Sack of Constantinople (2004) is that the diversion was made under impossible financial pressure, with several bad options and no good ones. The position associated with Donald Queller’s The Fourth Crusade: The Conquest of Constantinople (1977) is somewhere in between: the Venetians did not plan the diversion, but they exploited it. All three readings have merit; the truth is that the diversion was a sequence of contingent decisions, not a single grand design.

Origins: a clean plan that did not survive contact with the cost

The Fourth Crusade was called by Pope Innocent III in August 1198 in the bull Quia maior, which is one of the most carefully argued papal documents of the Middle Ages. Innocent was one of the most powerful medieval popes, and he had ambitious plans for the papacy. The new Crusade was to recapture Jerusalem, which had been in Muslim hands since Saladin’s reconquest in 1187, and it was to be led by the most powerful rulers of Europe.

The response to Innocent’s call was good. The kings of France, England, and Germany all took the cross in the years that followed. The principal leader of the expedition was Boniface of Montferrat, an Italian nobleman who had served the Holy Roman Empire. The most important figure, however, was not a military leader but the Doge of Venice, Enrico Dandolo, an elderly and nearly blind statesman who would shape the entire expedition.

The army of the Fourth Crusade was smaller than that of the Third Crusade, but it was still a substantial force. The French contingent, which would form the bulk of the army, was led by Count Hugh of Saint-Pol, Count Louis of Blois, and others. The Italian contingent was led by Boniface of Montferrat. The army numbered perhaps 10,000 to 15,000 effective combatants, plus a substantial non-combatant train.

The contract with Venice

The army faced a logistical problem: it needed ships to transport it to the Holy Land. The Crusaders contracted with Venice, the dominant naval power in the Eastern Mediterranean, to provide the necessary transport. The agreement, signed in early 1201, called for Venice to provide ships for 4,500 knights, 9,000 squires, and 20,000 foot soldiers, with provisions for nine months.

The cost of the agreement was enormous: 85,000 silver marks, more than the entire annual revenue of the French crown. The Crusaders were able to raise only about half of the sum before they arrived in Venice. The shortfall would have dramatic consequences.

The Venetian role in the Fourth Crusade was crucial. The Republic of Venice had been founded on the trade between Western Europe and the Eastern Mediterranean, and the Crusader States were an important market for Venetian goods. The Venetian leadership was also politically sophisticated, and they had long experience in negotiating with the Byzantine Empire. The role of Venice is examined in What was the role of Venice in the Fourth Crusade.

The diversion to Zara

The Crusader army gathered in Venice in 1202. The shortfall in payments was a serious problem. The Venetians, led by Doge Enrico Dandolo, offered a solution: the Crusaders could pay off their debt by helping Venice to capture the Adriatic port of Zara, which had recently rebelled against Venetian rule. Zara was a Christian city, and the attack on it was a violation of the papal ban on Crusaders attacking fellow Christians. Pope Innocent III protested, but the Crusaders proceeded with the attack in November 1202.

The capture of Zara was a disaster for the moral authority of the Crusade. Innocent excommunicated the entire army, although the excommunication was later lifted for the French Crusaders who had not consented to the attack. The episode set a precedent for the diversion of the Crusade to other targets, and it showed that the leadership of the expedition was willing to put pragmatic considerations above religious ones.

The attack on Zara also had a more immediate consequence. The Crusaders were now even more deeply in debt to Venice, and they needed to find a way to pay off the new obligations. The solution would come from an unexpected source: the Byzantine Empire, where a claimant to the throne was willing to pay for the support of the Crusader army.

The Byzantine appeal

The Byzantine Empire in 1203 was in the midst of a succession crisis. The emperor Isaac II Angelos had been deposed, blinded, and imprisoned by his brother Alexios III. Isaac’s son, Alexios the Younger (also called Alexios IV), escaped from Constantinople and made his way to the Crusader camp. He offered the Crusaders a substantial sum of money, military support, and the reunion of the Greek and Latin churches, in return for their help in restoring his father to the throne.

The offer was tempting. The Crusaders needed money to pay off their debt to Venice, and the union of the churches had been a long-standing goal of the papacy. The leadership of the expedition, especially Enrico Dandolo, decided to accept. The army set sail for Constantinople in April 1203, and arrived in June 1203.

The first siege of Constantinople, in July 1203, was a success. The Crusader army, with Venetian ships supporting the assault, broke through the chain that protected the Golden Horn, and the city was thrown into chaos. Alexios III fled, and Isaac II was restored to the throne. Alexios IV, who had been the cause of the diversion, was now co-emperor.

The failed union and the second siege

The restoration of Isaac and Alexios IV did not solve the problems of the Crusaders. The new regime was unable to pay the sums promised, and the relationship between the Latin and Greek populations of Constantinople deteriorated rapidly. The Greek population was deeply hostile to the idea of union with Rome, and the new regime was unable to enforce the agreement. By late 1203, the situation was hopeless.

In January 1204, a palace coup overthrew the regime of Isaac and Alexios IV. The new emperor, Alexios V Doukas Murzuphlos, took power and refused to honour the agreement with the Crusaders. The Crusaders were now without a pretext for their presence, and they were still deeply in debt to Venice. The leadership of the expedition, especially the Venetians, decided to take the city by force.

The Sack of Constantinople in 1204 is one of the most notorious events in medieval history. The Crusader army and the Venetian fleet launched a coordinated assault on 9 April 1204. The city was defended by a substantial garrison, but the walls were eventually breached. The Crusaders and Venetians poured into the city on 12 April 1204, and for three days the greatest Christian city in the world was subjected to a systematic pillage.

The three days of the sack

The sack was a catastrophe. The Crusaders and Venetians looted the city’s churches, monasteries, and palaces. The famous library of Constantinople was destroyed. The relics of saints were seized, including the Crown of Thorns and other sacred objects that would later be venerated in Western Europe. The great bronze horses of the Hippodrome, which had stood above the city’s hippodrome since antiquity, were taken to Venice, where they still stand above the entrance to St. Mark’s Basilica. The population of the city was killed, raped, or sold into slavery. The damage to the city’s infrastructure was so severe that Constantinople would never fully recover.

The sack of Constantinople was a major turning point in the history of the medieval world. The Byzantine Empire, although it would survive in exile for another 57 years, was fatally weakened. The Greek Orthodox Church was split from Rome in a way that would last until modern times. The cultural treasures of Byzantium were dispersed across Europe, and the Latin West gained access to the wealth of Greek learning that would eventually fuel the Renaissance.

The sack was also a major blow to the moral authority of the Crusades. Pope Innocent III condemned the sack, but he was unable to prevent it. The papacy had been a driving force behind the Fourth Crusade, and the failure of the expedition to achieve its central objective was a major embarrassment. The legacy of 1204 would shape the relationship between the Latin and Greek churches for centuries.

The Latin Empire of Constantinople

The sack of Constantinople was followed by the establishment of the Latin Empire of Constantinople. Baldwin of Flanders, one of the leaders of the Fourth Crusade, was crowned the first Latin Emperor of Constantinople in May 1204. The empire was formally established on the basis of a partition agreement signed between the Crusaders and the Venetians.

The Latin Empire would survive for 57 years, until the Byzantines recaptured Constantinople in 1261. The empire was always fragile, dependent on the support of Western Europe and threatened by the resurgent Greek states in the East. The empire’s fall in 1261 was a major blow to the Latin Church, and it would set the stage for the eventual Ottoman conquest of the city in 1453.

The personal and the structural

The Fourth Crusade is one of those episodes in which the personal and the structural explanations both have weight. On the personal side, the decisions of specific individuals mattered: Enrico Dandolo, the blind Doge, was determined to extract a return for Venice’s investment; Alexios IV, the young prince, made promises he could not keep; Boniface of Montferrat, the nominal leader of the Crusade, had long had designs on the Byzantine throne. On the structural side, the financial pressure of the contract with Venice, the political instability of the Byzantine Empire, and the absence of papal control all created the conditions in which bad decisions could be made and not corrected.

A point that older narratives often miss: the Crusaders themselves, at least in the French leadership, were not cynically commercial. Many of them were genuinely horrified by the sack, and some of the most powerful voices against it were in the army. Hugh of Saint-Pol and others protested. Even the Venetians were divided. The Fourth Crusade is, in this sense, not a story of a clean gang of thieves but a story of a movement that lost control of itself.

The legacy

The Fourth Crusade is also significant for its impact on European culture. The sack of Constantinople brought a vast amount of Greek learning to the West, including the works of Aristotle, Plato, and many others. The transmission of Greek texts, especially through the work of scholars like William of Moerbeke, was a major factor in the development of Scholasticism and eventually of the Renaissance. The Fourth Crusade, in this sense, had effects that extended far beyond the immediate political and military events of 1204.

The Fourth Crusade is, in many ways, the failure of the Crusading ideal. The expedition had been called to recapture Jerusalem, and it had ended in the sack of a Christian city. The diversion of the Crusade, the attack on Zara, and the sack of Constantinople were a series of moral failures that would have profound consequences for the Crusading movement and for the relationship between the Latin and Greek churches. The Fourth Crusade, in this sense, is the moment when the Crusading ideal most decisively failed in its central religious purpose, and the memory of 1204 has shaped the way historians understand the entire movement ever since.