The judgement of Paris.

In celebration of the marriage of Peleus and Thetis, Lord Zeus, father of the Greek pantheon, hosted a banquet on Mount Olympus. Every deity and demi-god had been invited, except Eris, the goddess of strife; no one wanted a troublemaker at a wedding. For revenge, Eris threw the golden Apple of Discord inscribed with the word "Kallisti" — "For the most beautiful one" — into the party, provoking a squabble among the attendant goddesses over for whom it had been meant.

The goddesses thought to be the most beautiful were Hera, Athena, and Aphrodite, and each one claimed the apple. They started a quarrel so they asked Zeus to choose one of them. Knowing that choosing any of them would bring him the hatred of the other two, Zeus did not want to take part in the decision. He thus appointed Paris to select the most beautiful. Escorted by Hermes, the three goddesses approached Paris as he herded his cattle on Mount Garagarus. They immediately attempted to bribe him to choose among them - Hera offered ownership of all of Europe and Asia; Athena offered skill in battle, wisdom and the abilities of the greatest warriors; and Aphrodite offered the love of the most beautiful woman on Earth, Helen of Sparta. As if further convincing arguments were needed, Aphrodite then let her robe fall, exposing her nudity. Paris chose Aphrodite—and Helen.

Helen was already married to King Menelaus of Sparta, so Paris had to raid Menelaus's house to steal Helen from him. (According to some accounts, she fell in love with Paris and left willingly.) The Greeks' expedition to retrieve Helen from Paris in Troy is the mythological basis of the Trojan War. This triggered the war because Helen was famous for her beauty throughout Achaea (ancient Greece), and had many suitors of extraordinary ability. Therefore, following Odysseus's advice, her father Tyndareus made all suitors promise to defend Helen's marriage to the man he chose for her. When she disappeared to Troy, Menelaus invoked this oath. Helen's other suitors—who between them represented the lion's share of Achaea's strength, wealth and military prowess—were obligated to help bring her back. Thus, the whole of Greece moved against Troy in force. The Trojan War had begun.