The achievements of the Third Crusade should never be under-estimated. The disaster at Hattin had destroyed the native Christian forces in the crusader kingdoms, and within months nothing was left of the Kingdom of Jerusalem except the city of Tyre. Yet by the end of the Third Crusade, the crusader kingdoms had been re-established, and indeed strengthened by the establishment of a Latin Kingdom on the island of Cyprus that provided the crusader kingdoms with a secure source of food and protection from Muslim fleets.
Castle of Kantara -- just one of the great fortresses on the island
Nevertheless, Jerusalem had been lost, and this inevitably altered the dynamics of crusading in the following century. Saladin had proved that the Christian kingdoms were vulnerable, and this made it easier for subsequent Muslim leaders to inspire to their followers with religious zeal. Meanwhile, in the West, crusaders and crusading had lost the aura of invincibility. Men increasingly doubted God’s Will when it came to the crusades. But the process was slow. Five more crusades – or six depending on how one counts – occurred before the last outpost of Outremer fell to the Saracens in 1291.
The first of these crusades was preached by Pope Innocent III already in 1198. Enthusiasm for this crusade was notably diminished compared to the three earlier ones. No king, nor any important nobleman, was prepared to lead it, and financing was so short that when the crusaders reached the port of embarkation, Venice, they were unable to pay for transport. The Venetians offered to provide the shipping for “free” – in exchange for crusader help in eliminating their (Christian) commercial rival, the city of Zara. Over the vehement protest of many participants and after much soul-searching, the crusade’s commanders agreed to do Venice’s dirty work, but they were no closer to Jerusalem.At this juncture, a deposed Byzantine emperor sought the aid of the crusaders, alleging that he would be welcomed with jubilation by the people of Constantinople and offering huge rewards. The crusaders took Constantinople, only to find that the people did not welcome the deposed prince. A coup soon brought another emperor to power, one hostile to the crusaders, and the troops were unpaid and in worse straights than ever. At this juncture, Venice proposed taking the wealthy city of Constantinople on their own account, and on April 13, 1204, the erstwhile crusaders captured and sacked the greatest Christian city in the world.
Although this action was repudiated by the Pope and reviled by many devout Christians throughout Western Europe, the damage had been done. Although Western barons held control of Constantinople and much of what is modern Greece for 60 years, all hope of unity between the Eastern and Western churches was destroyed, and the strength of the Byzantine Empire as a bulwark against Islam was broken.