The Oath of Tyndareus refers to a solemn vow made by the suitors of Helen, daughter of Tyndareus, King of Sparta, to defend the chosen husband against any wrongs or challenges to his claim. This oath is significant as it sets the stage for the events leading to the Trojan War, emphasizing themes of honor, loyalty, and the consequences of promise. The oath showcases the binding nature of alliances in Greek mythology and highlights how personal choices can escalate into larger conflicts.