Roman emperor and German king; born Argentau, France, c.1182;died Harzburg, Germany in 1218. Son of Henry the Lion and nephew of Richard Coour de Lion, his succession, 1198, was contested by Philip of Swabia, the nominee of the Hohenstaufens. Philip's seizure of the See of Mainz caused Innocent III to support Otto who, in return, made generous concessions to the Holy See, thus aiding Innocent's ambition to be overlord of Italy. Public opinion turned toward Philip, however, 1204-05, and Innocent deserted Otto; Philip, triumphant, was murdered at Bamberg and Otto, by marrying his daughter, overcame all opposition. Crowned at Rome, 1209, he immediately laid claim to Sicily, was excommunicated, and Frederick II set up as his rival. Frederick was supported by France and the German princes and Otto's cause was lost by the defeat of his supporters at Bouvines, 1214. Before his death the ban of excommunication was raised.