Which Byzantine empress reversed the decrees against icon veneration in 843?

The correct answer is Theodora II, who played a pivotal role in the history of Byzantine iconoclasm. In 843, she successfully reversed the longstanding policies that opposed the veneration of icons, which had been a contentious issue within the Byzantine Empire. Theodora II, as a devout supporter of icon veneration, promoted the restoration of icons in churches and public spaces, leading to a significant event known as the "Triumph of Orthodoxy."

This victory for icon veneration was not merely a religious victory but also had profound political implications, as it helped to unify the empire and strengthen the authority of the Orthodox Church. Theodora’s actions positioned her as a key figure in Byzantine history, symbolizing the end of iconoclasm and the re-establishment of traditional religious practices that celebrated the use of icons in the Orthodox faith.

Overall, Theodora II's legacy is closely associated with the reinstatement of icon veneration, marking a significant moment in Byzantine religious and cultural history.