Battle of Ostia
849 CE.
Shown on the map at 41.750°, 12.283°.
The naval Battle of Ostia took place in 849 in the Tyrrhenian Sea between a Muslim fleet and an Italian league of Papal, Neapolitan, Amalfitan, and Gaetan ships. The battle ended in favor of the Italian league, as they defeated the Muslims. It is one of the few events to occur in southern Italy during the ninth century that is still commemorated today, largely through the walls named after Leo and for the Renaissance painting Battaglia di Ostia by Raphael.
Text from the Wikipedia article Battle of Ostia, licensed CC BY-SA 4.0.