Battle of Leuctra
The second major challenge Sparta faced was fatal to its hegemony, and even to its position as a first-rate power in Greece. As the Thebans attempted to expand their influence over Boeotia, they inevitably incurred the ire of Sparta. After they refused to disband their army, an army of approximately 10,000 Spartans and Pelopennesians marched north to challenge the Thebans. At the decisive Battle of Leuctra (371 BC), the Thebans routed the allied army. The battle is famous for the tactical innovations of the Theban general Epaminondas.