 Crowned King in Germany, Charles sided with Pope Leo X and declared Martin Luther an outlaw at the Diet of Worms (1521).The same year Francis I of France, surrounded by the Habsburg possessions, started a conflict in Lombardy that lasted until the Battle of Pavia (1525) led to his temporary imprisonment.The Protestant affair re-emerged in 1527 as Rome was sacked by an army of Charles's mutinous soldiers, largely of Lutheran faith.