The Battle of Mantinea was a battle in the Peloponnese War in 418 BC. between Sparta and Athens.
In 420 BC. Athens, Argos, Mantinea and Elis closed a covenant with Sparta. The Spartan king Agis II gathered an army at Philus and marched in the winter of 419 BC. to Argos. In 418 BC. Occupy the Argiven Orchomenus and an Athenian army under Laches Siege Tegea. Sparta, asked for help to allies Corinthia, Boeotia, Phocis and Locris, but they could not send an army in the vicinity of Argos and Orchomenus. This area of Arcadia was occupied by the Athenian army.
Meanwhile, Athenian ally Elis attacked the city of Lepreum, agis plundering with a Spartan army of 9,000 hoplites through Arcadia. In September 418 BC. Both Armies met on the plain of Mantinea, Sparta and Arcadia formed 6,000 soldiers left flank and Tegae with 3,000 soldiers and cavalry the right flank. Athens and Argos put 4,000 hoplits on the left flank and Mantinea with 2,000 soldiers and Athenian allies from Arcadia. 2,000 soldiers with cavalry joined the right flank.
When the battle started, the hopes of Mantinea and Tegae broke on both right flanks. Agis II tried to strengthen the weakened flank with the Arcadian allies under Aristocles, the Athenian army was flown by the Spartans. After that, the hopes of Argos and Acardia were encircled. There arose panic and chaos, the Spartan army directed a massacre at the Argiven.
The Athenian army lost 1,100 soldiers (Argos and Acardia 700 men, Athens 200 men and Mantinea 200 men). Spartans lost 300 soldiers. The Spartan generals Laches and Nicostratus died during the fighting.
Sparta sent an emissary to Argos, the Argiven and Athenians accepted a ceasefire and Orchomenus was abandoned. King Agis II broke down the city walls of Mantinea and the population had to live in villages again. The Athenian army had lost its status of "invincibility."
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