Theophilos is the son of the Emperor Michael II and his wife Thekla, and the godson of Emperor Leo V the Armenian.

Michael II had crowned Theophilos co-emperor in 822, shortly after his own accession.

Unlike his father, Theophilos had received an extensive education and showed interest in the arts.

He had succeeded his father as sole emperor on October 2, 829.

Theophilos continues in his predecessors' iconoclasm, though without his father's more conciliatory tone, issuing an edict in 832 forbidding the veneration of icons.

He also sees himself as the champion of justice, which he had served most ostentatiously by executing his father's co-conspirators against Leo V immediately after his accession.

At the time of his accession, Theophilos had been obliged to wage wars against the Arabs on two fronts.

Sicily was once again invaded by the Arabs, who took Palermo after a yearlong siege in 831, established the Emirate of Sicily, and gradually continued to expand across the island.

The imperial response to the invasion of Anatolia by the Abbasid Caliph Al-Ma'mun in 830 had been led by the Emperor himself, but the Empire had been defeated and had lost several fortresses.

In 831, Theophilos had retaliated by leading a large army into Cilicia and capturing Tarsus.

The Emperor had returned to Constantinople in triumph, but in the autumn he was defeated in Cappadocia.