In 1198, Pope Innocent II called for another crusade, and in November 1199 a group of French knights took crusade vows. A treaty was made with the doge of Venice, Enrico Dandolo (who had been blinded in a pogrom against Latins in Constantinople) for aid in reaching the mideast. In 1202, when it became clear that they had fewer crusaders (and less money) than expected, some of the European forces seized the port of Zara from the king of Hungary, who was also under crusade vows, to earn their passage. In response Innocent III excommunicated the Venetians and forbade an attack on Byzantium This message did not arrive until too late, though whether or not it would not have made a difference is debatable.
The crusaders captured Constantinople in 1203 and put Alexius IV on the throne. In late January 1204, Murzuphlus soon seized the throne and named himself Alexius V; he subsequently ordered the crusaders to leave. The crusaders responded by retaking Constantinople, this time plundering it as well. They then founded the Latin Empire out of territory conquered from Byzantium. Byzantines formed a government in exile and managed to retake Asia Minor by 1235. In 1261 they recaptured Constantinople, ending the Latin Empire. The fighting, however, further weakened the Byzantine empire, and in 1453, the Ottoman Turks took over region, capturing Constantinople on May 29, 1453.
To see a summary of the Third Crusade and subsequent events, click here.
To see a summary of the Fifth Crusade and subsequent events, click here.
To see a more detailed listing of events of this period, click here.