* The Judgement of Paris: Paris was chosen by the goddess Aphrodite to be the judge in a beauty contest between Hera, Athena, and Aphrodite. Aphrodite promised him the most beautiful woman in the world in exchange for his vote, which he gave to her.
* Helen's Abduction: The "most beautiful woman" was Helen, wife of King Menelaus of Sparta. Paris, encouraged by Aphrodite, sailed to Sparta and kidnapped Helen, taking her to Troy.
* The Greek Response: King Menelaus, with the support of his brother Agamemnon, rallied the Greek armies to reclaim Helen and punish Troy for the abduction. This led to the ten-year siege of Troy, the events of the Trojan War.
Therefore, while the war had broader implications and other contributing factors, Paris's actions with Helen are considered the immediate spark that ignited the conflict.