Poseidon in the Trojan War

In Greek mythology, the Trojan War was a significant conflict between mortals. Poseidon sided with the Greeks in the Trojan War because he was enraged with Laomedon, the Trojan ruler. Zeus, Poseidon's brother, advises him to avoid the conflict while Zeus' wife Hera is a supporter of the Greek people and distracts Zeus so that Poseidon can intervene. When Zeus learns that Poseidon had interfered, he sends another god, Apollo, to aid Troy. At first, Poseidon aids the Greeks as they advance on the Trojans. The Trojans can now fight back against the Greek army thanks to his support.

Poseidon saves the Trojan Aeneas from death after the Greek warrior Achilles comes dangerously close to killing him. Poseidon does this because Aeneas is destined to become the ruler of the Trojans rather than die in battle.
Poseidon fights for the Greeks and eventually saves Achilles from drowning in the River Xanthos despite interfering to protect Aeneas' fate. Apollo, a warrior for the Trojans, is then challenged to duel him. Poseidon is upset with Apollo because, after being sent by Zeus to labor for Laomedon and the Trojans for a year, Laomedon refused to pay them in the end. Apollo is viewed as a coward by Poseidon for not taking revenge and for aiding the Trojans.