Agamemnon has just insulted Achilles in front of all the Achaeans, and, because of this incident, Achilles decides to return home rather than stay and fight with his own people. Returning to his tent, Achilles calls upon his mother, Thetis, a goddess, to beg Zeus for one favor:
'Persuade him, somehow, to help the Trojan cause, / to pin the Achaeans back against their ships, / trap them round the bay and mow them down. / So all can reap the benefits of their king-- / so even mighty Atrides can see how mad he was / to disgrace Achilles, the best of the Achaeans!' (1.485-490).
Rather than put his anger aside and continue to help in the battle, Achilles, being the best warrior, not only stops fighting, he summons his mother to ask Zeus to make his people suffer. His pride and arrogance overrun his rational thinking, and his attempt to make his own people suffer as he watches makes his disgusting behavior incomprehensible.
Zeus complies with Thetis' request, and the Trojans eventually force the Achaeans back to their ships. After many great losses, Agamemnon sends messengers to Achilles to ask the great warrior to rejoin the battle. Reviewing the gifts of Agamemnon, Achilles replies, "'I say no wealth is worth my life!'" (9.488). Although this is a noble statement, Achilles answers more out of anger