IV., pope from June 816 to January 817, succeeded Leo III. He did not continue Leo's policy, which was more favourable to the clergy than to the lay aristocracy. Immediately after his consecration he ordered the Roman people to swear fidelity to Louis the Pious, to whom he found it prudent to betake himself personally in the following August. After the coronation of Louis at Reims in October he returned to Rome, where he died in the beginning of the following year. His successor was Paschal I.