THE DAY SPARTA FELL

When asked why he forbade successive Spartan campaigns against the same foes, the legendary Spartan lawgiver and military reformer Lycurgus explained, “So that [the enemy] may not, by becoming accustomed to defending themselves frequently, become skilled in war.” The truth of that statement was borne out in 371 BC on a plain near the central Grecian village of Leuctra, where, after nearly a decade of seesaw conflict, battle-hardened Boeotian yeomen crushed Sparta’s elite peers, ending the latter’s hegemony of Greece.

Following its victory over Athens and its Delian League allies in the 431–404 BC Peloponnesian War, previously anti-imperial and noninterventionist Sparta became both imperialistic and interventionist. In 386 BC Persian King Artaxerxes II, eager to keep his belligerent Greek neighbors in check, reclaimed the buffer regions of Ionia and Cyprus, consolidated his control of the eastern Aegean and imposed a peace on the warring city-states, with the Spartans as his enforcers. Sparta used its status as hegemon, or leading city-state, to bully other city-states into accepting Spartan garrisons and military governors, even attacking some and imposing narrow oligarchies on them.

Thebes, a strong Spartan ally during the Peloponnesian War, suffered under the terms of the peace, which called for the dismantling of its Boeotian League—comprising nearly a dozen sovereign cities and townships. Furthermore, the Spartans installed an oligarchy in Thebes and garrisoned its fortified acropolis of Cadmea. The pro-Spartan government then subdued potential troublemakers, executing some and forcing others into exile, including an influential soldier-statesman named Pelopidas, who fled to Athens.

In 379 BC Pelopidas secretly returned to