When it became known in France that Peter of Courtenay was dead, his eldest son, Philip, Marquis of Namur, renounced the succession to the Latin empire of Constantinople in favor of his brother Robert, who set out to take possession of his distracted inheritance, which was then ruled by Conon of Béthune as regent. Crowned emperor on March 25, 1221 Robert, who was surrounded by enemies, appealed for help to the pope Honorius III and to the king of France Philip II; but meanwhile his lands were falling into the hands of the rival Despotate of Epirus and Empire of Nicaea.
Some little aid was sent from western Europe, but soon Robert was compelled to make peace with his chief foe, John Ducas Vatatzes, emperor of Nicaea, who was confirmed in all his conquests. Robert promised to marry Eudoxia, daughter of the late emperor of Nicaea, Theodore I Lascaris, a lady to whom he had been betrothed on a former occasion; however, he soon repudiated this engagement, and married a French lady, already the fiancée of a Burgundian gentleman. Heading a conspiracy, the Burgundian drove Robert from Constantinople, and early in 1228 the emperor died in Morea.
Yolanda of Flanders
John of Brienne