Source Verification: Poseidon

How did Poseidon end up ruling the sea instead of the sky or underworld?

After the Titanomachy, the three sons of Cronus cast lots for the world, as Poseidon himself explains in the Iliad: Zeus won the sky, Poseidon the sea, and Hades the world below, with earth and Olympus held in common. Poseidon treats this as making him Zeus's equal in his own sphere rather than his subordinate, a point he makes explicitly when Zeus tries to give him orders through a messenger.

Source: Homer, Iliad 15.187-193

Why did Poseidon lose the contest for Athens to Athena?

Poseidon struck the Acropolis with his trident and produced a saltwater spring; Athena planted the first olive tree. Zeus set the twelve Olympian gods to judge between the two gifts, and King Cecrops of Athens testified that Athena had planted hers first, which decided the verdict in her favor. The city took her name rather than his.

Source: Apollodorus, Library 3.14.1

Why was Poseidon so hostile to Odysseus in the Odyssey?

Odysseus blinded Poseidon's son, the Cyclops Polyphemus, while escaping his cave, and then made the mistake of shouting his own name back at the wounded Cyclops as his ship pulled away. Polyphemus used that name to call down a curse from his father, asking that Odysseus reach home late, having lost all his men, and find trouble waiting there - a curse the rest of the Odyssey largely fulfills.

Source: Homer, Odyssey 9.526-536

Did Poseidon ever fight on the losing side in a war among the gods?

In the Iliad's Theomachy, the gods split into factions to support either the Greeks or the Trojans, and Poseidon backs the Greeks. He faces Apollo directly on the battlefield but the two withdraw from the fight without striking a blow, unlike some of the other divine pairings, since Apollo declines to come to real blows with his uncle over mortals not worth a quarrel between gods.

Source: Homer, Iliad 21.435-460

Is Poseidon's temper connected to earthquakes as well as storms?

Yes - his epithet Earth-Shaker (Ennosigaios) is used throughout Homer specifically for his power to shake the ground, distinct from his control of the sea itself, and ancient audiences associated seismic activity with his anger or his physical passage across the earth. The trident functions as the instrument for both powers in the tradition, striking rock to split earth or open springs just as it stirs or calms the sea.

Source: Homer, Iliad 20.57-66

• Homer, Odyssey 9.526-536
• Homer, Iliad 15.187-193
• Apollodorus, Library 3.14.1

• Timothy Gantz, Early Greek Myth (1993)