Intense debate over the role of art in worship led eventually to the period of "Byzantine iconoclasm." Sporadic outbreaks of iconoclasm on the part of local bishops are attested in Asia Minor during the 720s. In 726, an underwater earthquake between the islands of Thera and Therasia was interpreted by Emperor Leo III as a sign of God's anger, and may have led Leo to remove a famous icon of Christ from the Chalke Gate outside the imperial palace. However, iconoclasm probably did not become imperial policy until the reign of Leo's son, Constantine V. The Council of Hieria, convened under Constantine in 754, proscribed the manufacture of icons of Christ. This inaugurated the Iconoclastic period, which lasted, with interruptions, until 843.