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.
When the news of this outrage reached the Thebans, they set out at once, under the guidance of two new Boeotarchs, to deliver their beloved fellow-citizen. Epaminondas, too, marched in the ranks; for, now that his term of office was ended, he had contentedly returned to his former obscure position.
The new Boeotarchs were unfortunately very poor generals. They met the Thessalian army, but were defeated and driven back. Indeed, the Thebans were soon in such danger, that the soldiers revolted against their generals, and begged Epaminondas again to take the lead.
As they were in great distress, Epaminondas could not refuse to help them: so he assumed the command, and beat such a skillful retreat that he brought them out of the country in safety.
The following year, when again chosen Boeotarch, Epaminondas made plans for a second campaign, and marched into Thessaly to deliver his friend, who was still a prisoner. When Alexander the tyrant heard that Epaminondas was at the head of the army, he was frightened, and tried to disarm the wrath of the Thebans by setting Pelopidas free, and sending him to meet the advancing army.
Of course, Epaminondas was very glad to see his friend; but when he heard how cruelly Alexander treated all his subjects, he nevertheless continued his march northward, hoping to rid the country of such a bad ruler. Just then the Spartans, in spite of their solemn promise, suddenly rose up in arms against the Thebans; and Epaminondas, leaving part of the army in Thessaly with Pelopidas, hurried southward with the rest to put down the revolt.