The Battle of Mantinea was fought in 362 BC between the Thebans, led by Epaminondas and supported by the Arcadians and the Boeotians, and the Spartans, led by King Agesilaus II and supported by the Eleans, Athenians, and Mantineans. The battle had to decide the hegemony over Greece, but the death of Epaminondas and the defeat of the Spartans paved the way for the Macedonian conquest.

After the battle of Leuctra in 371 BC had shattered the foundations of Spartan hegemony, there was an attempt by Thebes' chief politician and general Epaminondas to build a new hegemony centered on his city. To obtain this, the Thebans had marched south, into the area traditionally dominated by the Spartans, and set up the Arcadian League, a federation of city-states of the central Peloponnese plateau, to contain the influence of Sparta in the Peloponnese and thereby maintain overall Theban control. In the years leading up to the battle of Mantinea, the Spartans had joined with the Eleans (a minor Peloponnesian people with a territorial grudge against the Arcadians) in an effort to undermine the League. When the Arcadians miscalculated and seized the Pan-Greek sanctuary of Zeus at Olympia in Elis, one of the Arcadian city-states, Mantinea, detached itself from the League. The Spartans and Eleans joined the Mantineans in a military attack on the Arcadian League. Athens decided to support the Spartans, as she resented the growing Theban power. The Athenians also recalled that at the end of Peloponnesian War, the Thebans demanded that Athens was to be destroyed and its inhabitants to be enslaved. The Spartans however resisted these demands. An Athenian army was sent by sea to join the Spartan led forces, in order to avoid being intercepted on land by Theban forces. Epaminondas then led a Theban army into the Peloponnese to restore order and re-establish Theban/Arcadian hegemony there.

The two armies met near Mantinea in 362 BC. The Spartans, Athenians, Eleans and Mantineans were led by the Spartan king, Agesilaus II. The Theban army included other than Thebans also contingents from the other city-states of the pro-Theban Boeotian League. Epaminondas' Thebans were assisted by the Arcadians loyal to the League, principally those from the city-states of Megalopolis (founded by the Thebans when they were last in the Peloponnese, as the Arcadian federal capital) and Tegea (the traditional leading city-state of the Arcadians). Both generals were highly proficient, but Epaminondas prevailed on that occasion. Using a modified version of the tactics that he had successfully pioneered at Leuctra, he organised the Boeotian troops on the left wing of his army into an unusually deep column of hoplites (ancient Greek pikemen with heavy, brazen shields). He personally led this column from the front line. Xenophon described the left wing of that Theban army as "like a trireme, with the spur of the prow out in front."

Epaminondas charged and routed the Spartan right wing, winning the battle. Having fought in the front line, however, he was fatally wounded. The Theban leaders Iolaidas and Daiphantus, whom he intended to succeed him, were killed. On his deathbed, Epaminondas, on hearing of the deaths of his fellow leaders, instructed the Thebans to make peace, despite having won the battle. Without his leadership, the Theban hegemony was immediately ended. The Spartans, however, having been again defeated in battle, were unable to replace them. The ultimate result of the battle was to pave the way for the Macedonian conquest of Greece, by ensuring the weakness of both the Thebans and the Spartans.