Kaloyan of Bulgaria
Evidently in this same year of 1204, but after his new marriage, Boniface requested that he be allowed to exchange his lands in Asia for the Kingdom of Thessalonica, which he considered to be better suited for a political alignment with his new brother-in-law Andrew, then Regent of Hungary who would then be his neighbour, and the new emperor agreed to this exchange. Boniface however did not enjoy his domains in peace, being engaged in almost constant warfare until his death. Margaret's step-daughter Agnes of Montferrat was married to the new emperor, Henry of Flanders, in February 1207. That same year, Boniface was returning to Thessalonica when he was ambushed by Bulgarians. He was taken alive and decapitated, his head being sent to Kaloyan of Bulgaria.