Otto IV
Otto IV of the Welf dynasty was the only Welf Holy Roman Emperor. Crowned Holy Roman Emperor by Pope Innocent III in Rome in 1209, Otto immediately reneged on his promises to respect papal territorial claims and invaded southern Italy. Innocent III excommunicated Otto in 1210 and threw his support behind Frederick II. The decisive blow came at the Battle of Bouvines in July 1214, where Otto's ally King John of England was defeated by Philip II of France. Otto retreated to his hereditary Welf lands in Brunswick and died there in 1218.
- Lived: 1175 CE – 1218 CE
- Nationality: german
- Roles: emperor, head_of_state, military_leader
