 When his eldest brother, Philip II, Marquis of Namur died in 1226 without an heir, his second brother Robert was already Latin Emperor in Constantinople, so Henry became the new Margrave of Namur.At the time of his succession he was in France, under the guardianship of Enguerrand III, Lord of Coucy.When his brother Robert died in 1228, Henry renounced the title of Latin Emperor, which went to his younger brother Baldwin.