Constantinople gained much of its territory back in the Crusades. The Fourth Crusade was a crusade gone wrong. Shortly before, there had been a dispute between the Byzantine emperor and Venetian merchants in Constantinople, which resulted in a massacre of perhaps 10,000 Venetians by the Byzantines. In the course of it, a Venetian named Enrico Dandolo was deliberately blinded by the Byzantines, but made his way back to Italy.
Later, a usurper seized the throne of Constantinople from the emperor, Isaac Angelus, and blinded Isaac. Isaac’s son, Alexius, went to the West, where a movement was underway to undertake a new crusade to the Holy Land. Aleiux’ purpose was to enlist help to put his father back on the throne. Interestingly, Enrico Dandolo had, by that time, become the ruler of Venice. A deal was struck among the crusaders, largely Franks, Dandolo and Alexius. The crusaders did not have the money to pay Venice for transport to the holy land. There is some question that Dandolo hiked the price as a bargaining chip. So, Dandolo agreed to provide transport on credit if the crusaders would recapture a city that had been seized from Venice by Hungary. Alexius agreed to repay Venice if the crusaders would retake Constantinople and put Isaac back on the throne. He also agreed to resupply the crusaders at Constantinople, pay a cash sum for further support, reunite the Catholic and Orthodox churches and provide 10,000 Byzantine soldiers to aid in the crusade in the Holy Land, At that point, the Pope, hearing of the deal, protested and issued an excommunication against all crusaders who attacked any Christian city.
Ignoring the Pope, the crusaders accepted the deal and were transported to the city Venice wanted back, and took it. Venice then transported the crusaders to Constantinople, where they reinstated Isaac Angelus and his son, Alexius. However, when the Byzantines learned of the agreement Alexius had made, they refused to comply with it, leaving around 7,000 armed, angry, but massively outnumbered Franks to starve outside the city. The Byzantines fatally underestimated the fighting ability of the Franks and the craftiness of Enrico Dandolo, whose fleet also attacked by sea. The Franks and Dandolo’s Venetians conquered the City and looted it. In the course of the conquest and looting, around 2,000 Byzantines died. The Fourth Crusade never made it to the Holy Land; their original objective. It was a truly tragic event.
But far from being sanctioned by the Pope, it was condemned by him.
