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.
This sequence of events occurred on 14 March 815, when Leo forced Patriarch Nikephoros I to resign and appointed Theodotos Melissenos as his replacement. This led to a Church council in Constantinople later that year, which reversed the Second Council of Nicaea's decision and reinstated the ban on icon veneration, thus marking the beginning of the second period of Byzantine Iconoclasm.