Answer
Marcian was a Byzantine emperor who reigned from 450 to 457 AD. He reversed many of the actions of his predecessor, Theodosius II, who had been a staunch supporter of the monophysite heresy. Marcian instead supported the Chalcedonian Creed, which affirmed the orthodox Christian belief in the dual nature of Christ. He also restored the rights of the Orthodox Church, which had been persecuted under Theodosius II.