On 14 March 815, Leo forced the resignation of Patriarch Nikephoros I, and appointed the pro-iconoclast Theodotos Melissenos in his place. Later in 815, the new patriarch presided over a Church council in Constantinople, which overturned the Second Council of Nicaea and reinstated the ban on the veneration of icons, thus beginning the second period of Byzantine Iconoclasm.
In 815, Leo coerced Patriarch Nikephoros I into relinquishing his position, replacing him with Theodotos Melissenos, a staunch iconoclast. Subsequently, the new patriarch oversaw a Church gathering in Constantinople, which overturned the Second Council of Nicaea's ruling and reestablished the prohibition on icon veneration, thus initiating the second era of Byzantine Iconoclasm.