On September 2, 31 BC, the forces of Augustus defeated those of Mark Antony and Cleopatra VII in a decisive naval battle on the Ionian Sea near Actium. It marked the end of the Roman Republic and the beginning of the Roman Empire. To commemorate the victory of his fleet, Augustus set up a monument overlooking the site, which incorporated the bronze rams taken from the defeated ships. He also established a festival of Apollo, or it may have been the revival of an ancient one, with games called Actia, or Olympia. They were celebrated every four years at Nicopolis in Epirus with wrestling, musical contests, horse racing, and sea battles.