Battle of Leuctra and the Theban Hegemony
Sparta had not lost a major hoplite battle in living memory when its king Cleombrotus I led an army into Boeotia in 371 BCE to punish Theban resurgence following the Corinthian War settlement. Conventional hoplite battle pitted phalanxes of roughly equal depth against each other, with the strongest troops massed on the right; Epaminondas broke this convention by massing an extraordinarily deep column -- fifty ranks rather than the usual eight to twelve -- on his own left wing, opposite Sparta's elite right wing where the king himself fought. The overwhelming weight of the deep Theban column crushed the Spartan right before the rest of both lines had even engaged, killing Cleombrotus and roughly a quarter of Sparta's entire citizen-soldier (Spartiate) class in a single afternoon -- a demographic catastrophe for a state whose entire social system depended on a shrinking pool of full citizens controlling a vastly larger enslaved helot population. Epaminondas followed his victory by invading the Peloponnese itself, something no army had done in centuries, and permanently liberated the enslaved Messenian helot population that had underpinned Spartan military economics since the eighth century BCE, founding the independent city of Messene. Deprived of Messenian agricultural labour and having lost a generation of Spartiates at Leuctra, Sparta never recovered its former power, while Thebes briefly became the leading power in Greece under Epaminondas until his death in battle at Mantinea in 362 BCE, after which no single city-state again achieved lasting hegemony before Macedon imposed unity by force.
- Year: 371 BCE
- Category: Military
