Why did Ulysses have to fight in the Trojan war?

Ulysses, also known as Odysseus, was compelled to fight in the Trojan War due to his oath to protect Helen, the wife of Menelaus, after all the Greek leaders pledged to support him in case of her abduction. When Paris, a Trojan prince, eloped with Helen, this oath necessitated Ulysses' participation in the war alongside the Achaeans. Additionally, Ulysses sought to prove his bravery and secure his legacy as a hero, which further motivated his involvement in the conflict.