he Fourth Crusade (1202–1204) was originally intended to recapture Jerusalem from Muslim control but ended in the sack of Constantinople, the capital of the Byzantine Empire, in 1204. The crusade was called by Pope Innocent III at the start of his reign who urged the rulers of the European countries to raise armies and reclaim the Holy Land. The previous crusades had been led by kings, but this crusade was conducted by the feudal lords, mainly from France.

An agreement was made between the crusaders and Enrico Dandolo, the Doge of Venice to supply a fleet of ships to transport the army to the Holy Land. When more ships were built than were originally required, and the cost of the construction could not be met, the Doge saught to change the agreement and use the crusaders for his own political gains. The crusaders were required to attack the city of Zadar, previous known as Zara, now located on the coast of Croatia, which had renounced its allegiance to Venice. The crusaders cut the chains guarding the harbour and landed horses and siege engines and laid siege to the city. The city surrendered in under a week.