http://agathe.gr/democracy/military_service.html
Military Service After the 18-year-old was registered in his deme as a citizen and was approved by the Council, he entered military service as a young conscript (ephebe) with other members of his tribe ... They ran the torch race with dignity and grace. . . . ... Drawing of a lead cavalry tablet, fourth century B.C., registering a horse belonging to Konon, chestnut in color, with a centaur brand, worth 700 drachmas.