Why did the Fourth Crusade attack Constantinople?

Originally called by Pope Innocent III to recapture Jerusalem by defeating Egypt, the Fourth Crusade was diverted due to financial and political entanglements. After failing to pay the Republic of Venice for their transport fleet, the Crusaders agreed to attack the Christian city of Zara to settle debts, followed by an intervention in a Byzantine dynastic dispute. When their backed candidate was overthrown and killed, the Crusaders turned to the outright conquest and plunder of Constantinople in April 1204.

What we know

• The Fourth Crusade was originally intended to recapture Jerusalem by first defeating the Egyptian Ayyubid Sultanate. [2, 3]
• The Crusaders contracted a fleet from the Republic of Venice, but because fewer soldiers than expected arrived from other ports, they could not pay the contracted price. [2]
• Venetian Doge Enrico Dandolo proposed that the Crusaders help attack the rebellious city of Zara as an alternative to payment. [2]
• The Crusaders entered an agreement with Byzantine prince Alexios Angelos to divert to Constantinople to restore his deposed father, but after Alexios was murdered following a popular uprising, the Crusaders decided to conquer the city. [2]

Where to go next

• a case in pointWhat happened during the siege of Zara?
• what followedHow did the sack solidify the East-West Schism?
• whoWho was Pope Innocent III?
• the bigger pictureWhat was the broader history of the Crusades?
• whenWhen was Constantinople reconquered by the Byzantines?
• an unexpected connectionWhat is the IVth Crusade by Bolt Thrower?A British death metal band named one of their studio albums after this medieval military expedition.

Sources

• [1]Fourth Crusade (Wikidata Q51656) · CC0 1.0
• [2]Fourth Crusade · CC BY-SA 4.0
• [3]Crusades · CC BY-SA 4.0
• [4]The IVth Crusade · CC BY-SA 4.0
• [5]Fifth Crusade · CC BY-SA 4.0