Battle of Leuctra

In 371 BC, a Theban army defeated Sparta at Leuctra, in Boeotia, ending centuries of Spartan dominance on the battlefield. After Thebes refused to give up its leadership of the Boeotian cities, the Spartan king Cleombrotus I invaded with a larger army. The Theban general Epaminondas used a daring new tactic. Instead of spreading his troops evenly, he massed his infantry in an extremely deep column, reportedly fifty ranks deep, on his left wing, directly facing the elite Spartans on the enemy right. He held back his weaker right wing. At the front of the column fought the Sacred Band of Thebes, an elite unit of 300 soldiers led by Pelopidas. The heavy Theban column crashed into the Spartan line and broke it. Cleombrotus was killed along with around 400 of the 700 full Spartan citizens present, a devastating loss for a state with a shrinking number of citizens. Leuctra shattered the myth of Spartan invincibility. Thebes became the leading power in Greece, and Epaminondas soon invaded the Peloponnese and freed Messenia from Spartan rule.