against him to question his fitness to be emperor. Reign Rebellion of Artabasdos In June 742, while Constantine was crossing Asia Minor to campaign on the eastern frontier against the Umayyad Caliphate under Hisham ibn Abd al-Malik, his brother-in-law Artabasdos, husband of his older sister, Anna, rebelled. Artabasdos was the stratēgos (military governor) of the Opsikion theme (province) and had effective control of the Armeniac theme. Artabasdos struck against Constantine when their respective troops combined for the intended campaign; a trusted member of Constantine's retinue, called Beser, was killed in the attack. Constantine escaped and sought refuge in Amorion, where he was welcomed by the local soldiers, who had been commanded by Leo III before he became emperor. Meanwhile, Artabasdos advanced on Constantinople and, with the support of Theophanes Monutes (Constantine's regent) and Patriarch Anastasius, was acclaimed and crowned emperor. Constantine received the support of the Anatolic and Thracesian themes; Artabasdos secured the support of the theme of Thrace in addition to his own Opsikion and Armeniac soldiers. The rival emperors bided their time making military preparations. Artabasdos marched against Constantine at Sardis in May 743 but was defeated. Three months later Constantine defeated Artabasdos' son Niketas and his Armeniac troops at Modrina and headed for Constantinople. In early November Constantine entered the capital, following a siege and a further battle. He immediately targeted his opponents, having many blinded or executed. Patriarch Anastasius was paraded on the back of an ass around the hippodrome to the jeers of the Constantinopolitan mob, though he was subsequently allowed to stay in office. Artabasdos, having fled the capital, was apprehended at the fortress of Pouzanes in Anatolia, probably located to the south of Nicomedia. Artabasdos and his sons were then publicly blinded and secured in the monastery of Chora on the outskirts of Constantinople. Constantine's support of iconoclasm Like his father Leo III, Constantine supported iconoclasm, which was a theological movement that rejected the veneration of religious images and sought to destroy those in existence. Iconoclasm was later definitively classed as heretical. Constantine's avowed enemies in what was a bitter and long-lived religious dispute were the iconodules, who defended the veneration of images. Iconodule writers applied to Constantine the derogatory epithet Kopronymos ("dung-named", from kopros, meaning "faeces" or "animal dung", and onoma, "name"). Using this obscene name, they spread the rumour that as an infant he had defiled his own baptism by defaecating