Thebes was the main power in Greece after the brilliant victory at Leuctra, and for a short time the city managed to maintain its supremacy. By virtue of its position, it decided the destiny of less powerful cities; and when Alexander, tyrant of Thessaly, became very cruel, the Thebans sent Pelopidas to remonstrate with him.

Instead of treating the ambassador of the Thebans with courtesy, however, the Thessalian tyrant loaded him with heavy chains, put him in prison, and vowed he would keep him there as long as he lived.