274 BC

By place

Greece

• Pyrrhus returns from Italy and Sicily and invades Macedonia defeating Antigonus II Gonatas at the Battle of the Aous and conquering Upper Macedonia and Thessaly while Antigonus holds onto the coastal Macedonian towns. Antigonus' troops desert him and Pyrrhus is declared King of Macedonia.

  Roman Republic

• The Romans under Manius Curius Dentatus conquer the Lucanians.

  Egypt

• Magas of Cyrene marries Apama, the daughter of Antiochus and uses his marital alliance to foment a pact to invade Egypt. He opens hostilities against his half brother Ptolemy II, by declaring his province of Cyrenaica to be independent and then attacks Egypt from the west as Antiochus I takes the Egyptian controlled areas in coastal Syria and southern Anatolia, after which he attacks Palestine.
• Magas has to stop his advance against Ptolemy II due to an internal revolt by the Libyan Marmaridae nomads.