In classical mythology, which is the only source, the Achaean League was an alliance of the strongest of the Greek city-states and territories near the onset of the last millennium BC. The chief source for this is Homer (The Iliad and The Odyssey). According to Homer and other ancient sources, the Achaean League included:
- Mycenae, under the command of King Agamemnon
- Sparta, under the command of King Menelaus
- Ithaca, under the command of King Laertes and eventually under his son and successor Odysseus.
On or about 1032 BC, Paris, son of Priam, king of Troy, visited Sparta on a trade expedition. There he met Helen of Troy, wife and consort to Menelaus. The sketchier account suggests he abducted her, but most scholars of the Trojan War (who now consider this war a real event) say Helen ran away with Paris.
In any event, Menelaus immediately called upon his allies to help him get his queen back. And so the forces of the Achaean League, with Agamemnon in overall command, set out to conquer Troy.
Because Troy sat on the narrow passage between the Mediterranean Sea and the Euxine Sea (today called the Black Sea), most scholars suggest the overriding motivation was that the Achaean kings resented having to pay toll to the Trojans to gain access to the Euxine Sea and wanted to put an end to that practice.
This Trojan War, of course, lasted for ten years. And the return voyage was, if anything, more disastrous than the losses the Achaeans sustained in their ten-year siege of the city.