Arthur is portrayed as a Roman cavalry officer, also known as Artorius Castus, the son of a Roman father and a Celtic mother, who commands a unit of Sarmatian auxiliary cavalry in Britain at the close of the Roman occupation in 467 A.D. Arthur is loyal to Rome and a devout Catholic, but follows the teachings of Pelagianism, which many consider heretical. He and his men guard Hadrian's Wall against the Woads, a group of native Britons who are rebels against Roman rule, led by the mysterious Merlin.