The Iliad, Book 1

Chryses, having been rebuffed attempting to retrieve his daugher Chryseis from Agamemnon, pleads to Apollo to exact retribution on the Greeks.  It is done.  The Greeks plead to Agamemnon to relent.  He agrees, under the condition that he choose a replacement for Chryseis: Briseis, from Achilleus.  Hurt and angered, Achilleus vows withdrawal from the fighting.  He pleads to his mother, the goddess Thetis, to convince Zeus to exact revenge on Agamemnon and the Greeks by ensuring their defeat by the Trojans.