In our new animated historical documentary, we will describe the Fourth Crusade and the Sack of Constantinople in 1204. Although the First Crusade was succeeded in taking Jerusalem and a number of Frankish kingdoms were created in the Levant, by 1187 the Ayyubid leader Saladin managed to reconquer most of the region. The Third Crusade launched by the English king Richard I Lionheart, French king Philip II Augustus and German emperor Frederick I Barbarossa wasn't able to take Jerusalem, so the pope called for the Fourth Crusade led by Enrico Dandolo, Boniface of Montferrat and Baldwin of Flanders, which indeed up in one of the biggest tragedies for the Christian world.