During a massacre in this city, Cardinal John was beheaded and his head dragged through the street by a dog. According to Robert of Clari, Philip of Swabia was inspired to lay siege to this city after receiving the son of a deposed monarch. After a siege that captured this city’s Blachernae (“bla-CAIR-nay”) neighborhood, Baldwin IX was (10[1])crowned, (-5[1])beginning this city’s Frankokratia. The neighboring (10[1])town of Galata was used to stage an invasion of this city by Boniface of Montferrat. The Empire of Trebizond was created after that (10[1])sack, which was partly (10[1])prompted by unpaid debts to (10[1])Enrico Dandolo. The Latin Empire was established after a siege of this city that included the landing of soldiers on this city’s Golden Horn. (10[1])For 10 points, the Fourth Crusade sacked what capital of the Byzantine (10[1])Empire? ■END■ (10[1])