The Course of the Fourth Crusade (Edexcel A-Level History): Revision Notes
The Course of the Fourth Crusade
Introduction: an unexpected ending
The Fourth Crusade ended in a way that no one had anticipated. On 12 April 1204, instead of marching towards Jerusalem, crusaders were attacking the walls of Constantinople, the capital of the Byzantine Empire and the greatest Christian city in the world. A churchman named Aleaumes became the unlikely hero of this assault when he squeezed through a small gap in the city's defences, ignoring his brother's attempts to stop him. Despite breaking the rules against clergy bearing arms, he charged at the stunned defenders. Seventy crusaders followed him through, led by Peter, lord of Amiens, and together they opened one of the city gates.
The fact that a churchman led the breach of Constantinople's walls was particularly controversial. Medieval canon law strictly prohibited clergy from bearing arms or participating in violence, yet Aleaumes not only fought but became the hero of the assault. This violation of religious law highlighted how far the crusade had strayed from its original spiritual purpose.
Within hours, the crusaders had conquered Constantinople. They were not seeking aid or supplies as previous crusades had done—they were there to take the city by force. The Fourth Crusade thus became the first to end not in the Holy Land, but with the conquest of a fellow Christian empire.
The initial plan and recruitment (1198-1199)
In August 1198, Pope Innocent III issued his call for the Fourth Crusade. His vision was ambitious: he wanted a force led by kings or major nobles who would travel to Outremer (the crusader states in the East), continue the work of the Third Crusade, and recapture Jerusalem.
For a time, this goal seemed achievable. In November 1199, at a tournament held at Ecry, many nobles from France and Flanders answered the pope's call. Important figures like Thibault III of Champagne took the cross and committed to the crusade. These men immediately began planning their expedition and sent representatives to Venice to negotiate the details of their journey, which they did in March 1201.
The tournament at Ecry was a crucial recruitment event. Tournaments were not just sporting contests but important social gatherings where nobles displayed their military prowess and made political commitments. The decision to "take the cross" was a solemn religious vow that could not easily be broken.
Early problems and the Venetian agreement (1201-1202)
However, serious problems soon emerged that would derail the entire campaign.
First, Thibault III died in May 1201, depriving the crusade of one of its most influential leaders. Second, many other crusaders decided to make independent travel arrangements to Outremer rather than joining the main force. As a result, when the crusaders gathered in Venice in June 1202, their numbers were far smaller than expected.
The Financial Crisis: A Critical Turning Point
The shortage of crusaders at Venice created an insurmountable financial problem. The crusading leaders had negotiated a contract with Venice based on expected numbers that never materialized. Without enough men to share the cost, they could not pay the agreed fee. This financial crisis became the primary reason the Fourth Crusade never reached Jerusalem—every subsequent diversion was an attempt to solve this debt problem.
This created a financial crisis. The crusaders had agreed to pay Venice a substantial fee for transport and supplies, but with so few men present, they could not raise enough money to honour their agreement. The situation appeared hopeless until Doge Enrico Dandolo, the ruler of Venice, proposed a solution.
The doge's proposal
Dandolo offered to postpone payment of the debt—but not cancel it—if the crusaders would help him recapture the Adriatic port city of Zara (modern-day Zadar in Croatia). Desperate and with few alternatives, the crusaders accepted his terms in September 1202.
The first diversion: Zara (November 1202)
In November 1202, the Fourth Crusade began its first major diversion from its intended purpose. Instead of sailing to the Holy Land, the crusaders attacked Zara and conquered it for Venice.
First Diversion from the Holy Land
The attack on Zara marked a dramatic departure from the crusade's original mission. For the first time, crusaders were fighting not against Muslims in the Holy Land, but against fellow Christians in a European city. This action earned Pope Innocent III's condemnation, yet the crusaders proceeded anyway, showing how desperate their financial situation had become.
However, this victory did not solve their fundamental problem. Dandolo's agreement had only delayed payment of their debt, not eliminated it. The crusaders still lacked the funds to continue their journey to Jerusalem and were now even further from their goal.
The second diversion: Constantinople (1203-1204)
Prince Alexius's offer (December 1202)
Under these difficult circumstances, the crusaders received what seemed like an attractive proposal in December 1202. An ousted Byzantine prince, Alexius, approached them with a deal: if they helped him claim the throne of the Byzantine Empire, he would provide them with money, supplies, and troops—everything they needed to complete their crusade to Jerusalem.
Prince Alexius's offer appeared to solve all the crusaders' problems at once. He promised to pay their debt to Venice, provide additional funds for the journey to Jerusalem, supply troops to strengthen their army, and even reunite the Eastern and Western Churches under papal authority. For crusaders desperate to fulfil their vows, this seemed like divine providence rather than another diversion.
Seeing no other way forward, the crusaders accepted this second diversion.
The attack on Constantinople (July 1203)
On 17 July 1203, the crusading army attacked Constantinople. The assault was successful—they forced Emperor Alexius III to flee the city and helped Prince Alexius claim the throne as Alexius IV.
The crusaders now expected to receive the promised rewards that would enable them to continue to Jerusalem. However, it soon became apparent that Prince Alexius had promised far more than he could actually deliver. He could not raise the money or provide the troops he had guaranteed.
Alexius IV's Broken Promises
Prince Alexius's inability to fulfil his promises was not simply bad faith—it was practically impossible. The Byzantine treasury did not contain the enormous sums he had pledged, and his subjects were deeply hostile to the Latin crusaders occupying their city. His promises had been made in desperation to secure the throne, but once crowned, he discovered he could not deliver them without destroying his own empire.
Crisis and coup (January 1204)
The situation in Constantinople became increasingly unstable. In January 1204, both Alexius IV and his father Isaac II were imprisoned by a nobleman called Murtzuphlus, who crowned himself Alexius V. This coup meant that the crusaders' arrangement with Alexius IV was completely void.
The crusaders became desperate. They had diverted twice, conquered a city for Venice, and helped install a Byzantine emperor—yet they still had no resources to reach Jerusalem and no way to pay their debts.
The final attack and aftermath (April-May 1204)
The sack of Constantinople (April 1204)
In April 1204, the crusaders made a fateful decision. Rather than abandon their position, they attacked Constantinople itself, determined to take by force what Prince Alexius had failed to provide. After a fierce siege, they breached the walls and captured the city.
The Sack of Constantinople: A Shocking Betrayal
What followed the capture was one of the most controversial events in medieval history. The crusaders systematically looted Constantinople for three days, stealing immense treasures, destroying priceless artworks, and desecrating holy sites. They ransacked churches, stole sacred relics, and committed acts of violence against the civilian population. This was not a liberation or a rescue mission—it was the brutal conquest and plunder of Christianity's greatest city by warriors who had taken vows to defend Christendom.
What followed was a devastating sack of Constantinople. The crusaders looted the city's immense wealth and stole many of its most sacred relics. This was a shocking development—crusaders attacking and plundering the greatest city in Christendom.
A new empire (May 1204)
By 16 May 1204, the crusaders were in complete control of Constantinople. They appointed Baldwin of Flanders as the ruler of their new empire, which they renamed Romania. They now faced the enormous task of securing and governing this vast territory.
In April 1205, while many ordinary crusaders returned home, the leaders began establishing themselves as the rulers of Romania. Peter of Capuano absolved the crusaders from their vow to travel to Jerusalem in 1205, officially ending the Fourth Crusade. Pope Innocent III was reportedly furious at this outcome.
Peter of Capuano's absolution was a pragmatic decision that acknowledged reality: the crusaders would never reach Jerusalem. By releasing them from their vows, he allowed them to return home or remain in Romania without being in a perpetual state of sin for breaking their crusading oath. However, this practical solution did nothing to change the fact that the crusade had completely failed its stated objective.
The crusade's failure
Complete Failure to Achieve the Original Objective
The Fourth Crusade's stated objective—to recapture Jerusalem—was never achieved. Diverted twice (first to Zara, then to Constantinople) and ultimately preoccupied with events in the former Byzantine Empire, the crusade had completely failed to meet the goal set by Pope Innocent III in 1198. Instead of strengthening Christendom against its external enemies, the crusade had weakened it by destroying the Byzantine Empire, creating lasting hostility between Eastern and Western Christians, and demonstrating that crusading vows could be abandoned when political and financial pressures became too great.
Key terms
Doge: The title given to the ruler of Venice, who held significant power and influence. Doges were elected from the ruling families of Venice and held their position for life. Enrico Dandolo was the doge who played a crucial role in diverting the Fourth Crusade.
Enrico Dandolo was an extraordinary figure—he was in his eighties and completely blind when he led the Venetian forces during the Fourth Crusade. Despite his age and disability, he was a brilliant strategist and diplomat who manipulated the crusade to serve Venetian commercial interests. His proposal to attack Zara and his support for the diversion to Constantinople were calculated moves to expand Venice's trading empire in the eastern Mediterranean.
Byzantium: The former name of Constantinople and another term for the Byzantine Empire. It covered the eastern half of the old Roman Empire and was centred on Constantinople, which had been founded in the 4th century by the Roman Emperor Constantine. By the 13th century, Constantinople was the largest city in Christendom, with around 500,000 inhabitants. It was renowned for magnificent buildings like the Hippodrome, the Great Palace, and the church of Hagia Sophia. Its strategic location where Europe met Asia and its formidable defences (protected by the Sea of Marmara, the Golden Horn, and massive walls) made it extremely difficult to capture but immensely valuable to control.
Constantinople's defences were legendary. The city was protected on three sides by water (the Sea of Marmara and the Golden Horn), and on the landward side by the massive Theodosian Walls—a triple line of fortifications that had repelled countless attacks over centuries. The fact that the Fourth Crusade successfully breached these defences was a testament to both the crusaders' military capability and the weakened state of the Byzantine Empire by 1204.
Timeline of the Fourth Crusade
- August 1198: Pope Innocent III issues the call for the Fourth Crusade
- November 1199: Tournament held at Ecry where many crusaders are recruited, including Thibault III of Champagne
- March 1201: Plans for transportation and destination negotiated with Venice
- May 1201: Count Thibald III of Champagne dies; the Fourth Crusade loses considerable support from France
- June 1202: Crusaders begin to gather in Venice, but numbers are inadequate to pay the treaty fee
- September 1202: Dandolo agrees to postpone payment if crusaders help him attack Zara
- November 1202: First diversion—crusaders capture Zara for Venice
- December 1202: Prince Alexius proposes an alternative destination for the Fourth Crusade, offering incredible incentives in return for help restoring his father to the Byzantine throne
- July 1203: Second diversion—crusaders attack Constantinople and force Emperor Alexius III to flee
- January 1204: Murtzuphlus imprisons Byzantine emperors Alexius IV and Isaac II and crowns himself Alexius V
- April 1204: Crusaders, responding to the overthrow of Alexius IV, attack and ransack Constantinople
- May 1204: Baldwin of Flanders is crowned emperor of Romania, the former Byzantine Empire
- 1205: Peter of Capuano absolves the crusaders from their vow to travel to Jerusalem; the pope is furious, but the Fourth Crusade is over
Remember!
Key Points to Remember:
- The Fourth Crusade was called in 1198 with the aim of recapturing Jerusalem, but it ended in 1204 with the conquest of Constantinople instead.
- Two major diversions derailed the crusade: first to Zara (November 1202) to help Venice, and second to Constantinople (1203-1204) to help Prince Alexius claim the Byzantine throne.
- Financial problems were at the heart of the crusade's diversion—too few crusaders gathered at Venice in June 1202, meaning they could not pay the agreed fee to the Venetians.
- Prince Alexius's failure to deliver his promised money, supplies, and troops led the crusaders to take desperate action and attack Constantinople in April 1204.
- The crusade's original objective was never achieved, making it a complete failure in the eyes of Pope Innocent III, even though the crusaders established a new empire called Romania.