While living in Antioch with his family, Zeno sympathised with the Monophysite views of Peter the Fuller, and supported him against his opponent, the Chalcedonian bishop Martyrius. Zeno allowed the arrival in Antioch of monks from nearby monasteries who increased the number of Peter's followers, and did not effectively repress their violence. Martyrius went to Constantinople to ask Leo for help, but, on returning to Antioch, he was informed that Peter had been elected bishop, and resigned (470). Leo reacted by ordering Peter into exile and addressing to Zeno a law that forbade the monks from leaving their monasteries or fomenting rebellion (1 June 471). In 470/471, Zeno had also to deal with an invasion of Tzanni, who attacked Roman Armenia.