June 1, 479 BC

2486 years since the Battle of Platea, where the united Hellenic army, under the command of Spartan Vice-King Pausanias, although outnumbered at least three to one, crashed the Persians and expelled them once and for all from Greece.

The first and only battle in ancient history were Sparta mobilized almost its entire reserves, offering an army of 50,000 men, including 5,000 full citizens, 10,000 perioikoi and 35,000 helots.

More one wikipedia: http://en.wikipedia.org/wiki/Battle_of_Platea