 He based this theory on his own interpretation of Italian chronicles.The "Dictionnaire historique et Généalogique des grandes familles de Grèce, d'Albanie et de Constantinople" (1983) by Mihail-Dimitri Sturdza rejected the theory, based on the silence of Byzantine primary sources.In 1235, Angelo sent a naval squadron to the defence of Constantinople, where the Emperor John of Brienne was being besieged by John III Doukas Vatatzes, Emperor of Nicaea, and Ivan Asen II of Bulgaria.