Why was Helen called the Helen of Troy?

Helen was called the Helen of Troy because she was famously associated with the Trojan War, as depicted in Greek mythology and literature. According to the myth, she was considered the most beautiful woman in the world, and her abduction by Paris, a Trojan prince, led to the ten-year conflict between the Greeks and Trojans. Her beauty and the resulting war made her a central figure in stories such as Homer's "Iliad," solidifying her title as the Helen of Troy.