The man who defeated the Spartans.

The man often credited with decisively defeating the Spartans in battle is Epaminondas of Thebes. Epaminondas was a Theban general and statesman who transformed the balance of power in ancient Greece through his military innovations and strategic genius.

In 371 BCE, at the Battle of Leuctra, Epaminondas led the Theban forces to a historic victory over the Spartans, ending Sparta's long-held military supremacy in Greece. This battle is particularly notable for Epaminondas's tactical innovations. He employed an oblique battle formation where he concentrated his forces on the left wing, with the elite Sacred Band of Thebes at the forefront, creating a deep, heavy infantry column that overwhelmed the Spartan right wing. This was a departure from the traditional Greek battle line, which was uniformly deep across the entire front.

The victory at Leuctra was not just a military defeat for Sparta; it was a significant psychological and political blow, leading to Sparta's decline as the dominant power in Greece. Epaminondas followed this up by leading campaigns into the Peloponnese, liberating Messenia from Spartan control, which had been a source of helot labor for Sparta. This further weakened Sparta, as Messenia had been a key part of their economy and military structure.

Epaminondas's approach to warfare included not only tactical innovations but also a strategic vision that aimed at reshaping the Greek political landscape. He promoted the idea of a federation of Greek states under Theban leadership, challenging the old order dominated by Sparta.

His legacy is one of a military genius who changed the course of Greek history, demonstrating that even the seemingly invincible Spartan military machine could be outmaneuvered and defeated through superior strategy and innovative tactics. Epaminondas's contributions to Theban power, however, were cut short when he was killed in battle in 362 BCE at Mantinea, but his impact on Greek military history and politics remained profound.