Which god saved Aeneas from being killed by Achilles?

Poseidon saved Aeneas from being killed by Achilles in Homer's Iliad. In Book 20, Aeneas confronts Achilles, but the Greek hero quickly gains the advantage and prepares to strike him down. Poseidon intervenes because Aeneas has a destiny beyond the immediate battle.

The sea god lifts Aeneas away from the battlefield and places him safely elsewhere, despite generally supporting the Greek side during the Trojan War. Poseidon explains that Aeneas belongs to a branch of the Trojan royal family and is fated to survive so that he can become a future ruler of the Trojan people. The rescue therefore serves a larger divine plan rather than simply rewarding Aeneas' battlefield skill.

Aeneas is also protected earlier in the poem by his mother Aphrodite and the god Apollo when Diomedes nearly kills him. Readers sometimes confuse that episode with the later rescue by Poseidon. The Iliad does not tell the full Roman story of Aeneas founding a dynasty in Italy; that expanded destiny belongs chiefly to Virgil's much later Aeneid.