the Greek emperor of Thessalonica, A. D. 1222-1230, was descended from a noble family, being the son of Joannes Angelus, also called Comnenus, and the grandson of Constantinus Angelus.
After the overthrow of the Greek empire by the Latins in 1204, Theodore Angelus served for some time under Theodore Lascaris, the emperor of Nicaea, but afterwards passed over to Europe to join his bastard brother Michael, who had established an independent principality in Epeirus. On the death of Michael he succeeded to his dominions, which he greatly enlarged by the conquest of Thessaly, Macedonia, and other surrounding countries.
He took Peter of Courtenay prisoner, who had been elected emperor of Constantinople, as he was travelling through Epeirus to the imperial city, and kept him in captivity till his death [PETRUS]. Elated by his numerous successes, Theodore assumed the title of Emperor of the Romans, and was crowned at Thessalonica in 1222, in the same year that Joannes Vatatzes succeeded to the imperial title at Nicaea, and Andronicus at Trebizond.
He carried on war with success against the Latins, took Adrianople, and advanced as far as the walls of Constantinople.
He was, however, recalled to the defence of his own dominions by an invasion of Asan, king of the Bulgarians, who defeated him in battle, took him prisoner, and deprived him of his eyes, in 1230. During his captivity among the Bulgarians, his brother Manuel had seized his dominions and assumed the title of emperor; but Theodore having obtained his liberty, gained possession of Thessalonica by stratagem, and deposed his brother.
In consequence of the loss of his sight, he conferred the title of emperor upon his son Joannes; but the latter was subsequently conquered in the lifetime of his father by Joannes Vatatzes, the emperor of Nicaea, who compelled him to renounce the imperial dignity, and to content himself with the rank of despot. [JOANNES III.] (Acropolita, cc. 14, 21, 25, 26, 38, 40, 42; Du Cange, Familiae Byzantinae,