With the death of Theoktistos, the regency was at an end; in early 856, Michael proclaimed his assumption of full imperial power, and in 857 Theodora was forced to retire to the Gastria Monastery. Nevertheless, as Michael was more interested in his pleasures and his continuing affair with Eudokia Ingerina, Bardas now became the "de facto" regent of the Empire. By he was promoted to the highest state offices ("magistros" and "chartoularios tou kanikleiou"), followed by his promotion to "kouropalates"—according to Symeon the Logothete, this happened after a failed assassination attempt masterminded by Theodora—and finally, on 22 (or 26) April 862, to "Caesar". The dominance of Bardas is corroborated by non-Byzantine sources: al-Tabari records that Arab envoys negotiated with Bardas, rather than the emperor, and Bar Hebraeus writes that during an audience with an Arab embassy, Michael did not utter a single word, with his "cousin" (most likely Bardas) speaking on his behalf. Petronas also emerged from obscurity at the same time, becoming "strategos" of the Thracesian Theme and leading a series of successful raids against the Arabs.