Photios I of Constantinople
Born at Gallese, Marinus was the son of a priest. He was ordained as a deacon by Pope Nicholas I. He first served as bishop of Caere. On three separate occasions he had been employed by the three popes who preceded him as legate to Constantinople, his mission in each case having reference to the controversy started by Patriarch Photios I of Constantinople. In 882, he was sent on behalf of Pope John VIII to Duke Athanasius of Naples to warn him not to trade with the Muslims of southern Italy.