The Iliad: Novel Summary: Chapters 13-14
Chapter 13: Posiedon, god of the sea, appears to the Greeks in the form of Calchas the prophet, and motivates them to continue fighting. Ajax helps Posiedon, and the Greeks fight alongside their ships. The Greeks hold the Trojans back.
Chapter 14: Agamemnon again suggests retreat, and Odysseus and Diomedes oppose him, and the Greeks stay. Hera, Zeus' wife, drugs him so Posiedon can assist the Greeks without interference from Zeus.