King of the Myrmidons (in Thessaly), the hero of Homer's epic poem called the Iliad. He is represented as brave and relentless. The poem begins with a quarrel between him and Agamemnon, the commander in chief of the allied Greeks: in consequence of which Achilles refused to go to battle. The Trojans prevail, and Achilles sends forth his friend Patroclos to oppose them. Patroclos fell; and Achilles, in anger, rushing into the battle killed Hector, the commander of the Trojans. He himself, according to later poems, fell in battle a few days afterwards, before Troy was taken.
Mistress in Troy:
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894