What happened 256 AD

During his Danube sojourn (Drinkwater suggests in 255 or 256), he proclaimed his elder son Valerian II caesar and thus official heir to himself and Valerian I; the boy probably joined Gallienus on the campaign at that time, and when Gallienus moved west to the Rhine provinces in 257, he remained behind on the Danube as the personification of Imperial authority.

Romans launched an invasion of North Africa in 256 BC, which the Carthaginians intercepted at the Battle of Cape Ecnomus off the south coast of Sicily. The Carthaginians were again beaten.

The Battle of Cape Ecnomus or Eknomos was a naval battle, fought off southern Sicily, in 256 BC, between the fleets of Carthage and the Roman Republic, during the First Punic War. The Carthaginian fleet was commanded by Hanno and Hamilcar; the Roman fleet jointly by the consuls for the year, Marcus Atilius Regulus and Lucius Manlius Vulso Longus.

The Bactrian Kingdom was the easternmost part of the Hellenistic world, in Central Asia and the Indian Subcontinent from its founding in 256 BC by Diodotus I Soter to its fall under the reign of Heliocles II.