The Crusade continued from 1202 to 1204. However, the Crusader army became embroiled in several other conflicts along the journey to the Holy Land.
The most notable among these was the conquest and sacking of Constantinople. The Fourth Crusade was a decisive event in cementing the schism between the Eastern and Western churches.
The Third Crusade had ended with considerable military successes for the Crusaders. However, the city of Jerusalem remained in the hands of the Muslims.
In 1202, Pope Innocent III called for another crusade to recover the holy city for Christendom. The bulk of the Crusaders for the Fourth Crusade came from France, Flanders, and the Holy Roman Empire.
Notable leaders of the crusaders included Boniface of Montferrat and Enrico Dandolo, the Doge of Venice.
The original plan of the Crusader army was to bring together all the soldiers, knights, and resources at Venice. The state of Venice agreed to transport them across the sea to Egypt in return for a fee.
In 1202, the Crusader army gathered in Venice. However, only 12,000 men arrived as opposed to the expected 35,000 soldiers. The Venetians had made preparations to transport more than 30,000 men and they wanted full payment before transporting the Crusaders across the sea.
When the Crusaders couldn’t pay the money, the Venetians instead asked them to attack the city of Zara. Zara was a port city that competed with Venice for commerce. In November 1202, the Crusaders attacked Zara and pillaged it even though it had a Catholic population.
This led the Pope to excommunicate the Crusader army, although this ex-communication was later rescinded.
The Byzantine Empire was in political turmoil at the time. Emperor Isaac II Angelos had been deposed by his brother. Prince Alexius Angelos began negotiations with the Crusader army to restore his father to the Byzantine throne in return for rich favors.
The crusaders accepted the offer and arrived at the walls of Constantinople in June 1203.
The Crusader army successfully besieged the city and was able to have Emperor Alexios restored to the throne. However, both Alexios and his son were killed in 1204 after a popular uprising. The Crusaders didn’t receive the payment they had been promised, so they proceeded to plunder the riches of the city. The fall and sacking of the city eventually led to a fragmentation of the Byzantine Empire.
After the sack of Constantinople, the Byzantine Empire was broken up and divided among the Crusaders and the Venetians. This led to the establishment of the Latin Empire.
A number of other Crusader states also sprung up in the place of the former Byzantine Empire. This very nearly extinguished the Byzantine rule although a revival would later restore some portions of the Empire.
The Fourth Crusade failed in its stated objective of conquering Egypt, defeating the Ayyubids, and regaining control of Jerusalem. Instead, the most notable event of the Fourth Crusade was the sacking of Constantinople.
The city that was the crowning jewel of Christendom in the East was looted and plundered of all its riches, and burnt to ashes.
The Christian world at large was horrified at the event. This led to a deeper schism between the Catholic Church and the Eastern Orthodox Church.
It also depleted the strength of the Byzantine Empire. Although the Empire would later be restored, it could never regain its original strength and subsequently fell to the Ottoman Empire.