The δόλιχος was added to the Olympic games in the 15th Olympiad, and was, like our long runs, a test primarily of endurance and lung-power. The distance covered varied from seven to twenty-four laps of the stadion, or from less than a mile to about three miles. At Olympia, however, the distance was twelve stadia. As the δόλιχος was run on the same track on which the single and double races took place, it was really only a series of double races. In the 65th Olympiad, the ὁπλίτων δρόμος was introduced. In this race the competitors wore helmets and greaves, and carried shields on their left arms. Pausanias claims to have seen the statue of Demaratos equipped with a round shield, helmet and antique greaves. At a later period, however, the helmet and greaves were discarded at Olympia, and the race was run with shields alone. The distance covered in this race was two stadia--the length of the δίαυλος. Pindar, the poet laureate of the Olympians, mentions the race with shields, and with poetic privilege ascribes its origin to heroic times. Plato considered the exercise very valuable as war training, and prescribed it as a part of the athletics of his ideal commonwealth. Plato devised two other races involving armor: in one the competitor should be equipped as a heavy-armed hoplite, and should cover a distance of sixty stadia on a level plain; in the other the competitor should wear the light equipments of an archer, and should cover one hundred stadia over hills and valleys. The running contests at the great games were governed by certain established rules. No fraud or guile was allowed to be used by the contestant on the track for the purpose of impeding his companions. They were very particular that all should start at the same time and from the same line, so that no one might have the advantage over the others. It was also contrary to rule for an athlete voluntarily to slacken his speed and allow his fellow-contestants to win. The competitors were appointed by lot and arranged in groups. These groups raced in heats of four, ranged in the places assigned them by lot. The first group was followed by the second, the second by the third, etc. When all groups had finished, the victors of each again entered the contest and strove for the prize; so that every σταδιοδρόμος had to win twice before he was crowned victor.