In 1198, Pope Innocent III was elected to the papal throne. After the devastating loss of Jerusalem in 1187 to Saladin’s forces, Innocent made the recapture of the Holy City his primary concern and issued the call for a fourth Crusade. Christians saw Egypt as being the key to the recapture of Jerusalem because of its position as the military and economic powerhouse of the Near East: if Egypt fell then Jerusalem would follow. To reach Egypt, crusaders hired a fleet from Venice, who hosted the foremost naval power of the age. The costs of hiring the Venetian fleet were staggering and due to smaller than expected numbers taking the cross, the crusaders faced a huge financial shortfall.
Knowing the financial position of the crusaders, the Venetians sought to take advantage of the situation for their own cause. They offered the crusaders transportation in return for the recapture of Zara, a former Venetian possession. Zara was a Christian city and news of the potential attack outraged Pope Innocent. Even with papal protest the crusaders accepted the Venetians offer, deeming the shame of abandoning the crusade as too great. Whilst in Zara, the crusaders were approached with another offer, this time from a pretender to the Byzantine crown asking for their aid in overthrowing the Emperor. Again, with the lure of money, the crusaders accepted.
In July 1203, the crusaders landed in Constantinople, this was the largest amphibious assault yet attempted in the Medieval Age. By August, the crusader-backed usurper was Emperor Isaac II Angelos. He set about trying to seize the money promised to the crusaders from the people of Constantinople: the more he pressed for the people for money the harder they resisted. The result of this increasing tension was the murder of the new Emperor by Byzantine nobles and attacks on the crusader camps. Full scale conflict between the two sides was now inevitable. On April 12th 1204 the crusaders broke through the Byzantine defence and consolidated their position north of the City. Over the following three days the crusaders pillaged and looted the city while defenceless women and children were murdered in cold blood.
The result was not only the establishment of a series of Latin states in Greece and the Aegean Sea, but the permanent collapse of communion between Catholic and Orthodox Churches. The scars from 1204 have been so long lasting that it was only in 2004, 800 years after the event, that the Patriarch of the Orthodox church accepted an apology that was issued three years prior by Pope John Paull II regarding the horrors of the fourth Crusade.