Pheidon (Greek: Φείδων) was a king of Argos, Greece in the 7th century BC. At that time, the monarch was nominal with almost no genuine power. Pheidon seized the throne from the reigning aristocracy. He is considered in the tradition of other tyrants, like Gyges of Lydia, as an outsider to the ruling caste in some ways even though a fragment of the Parian Chronicle confirms him to have been a noble and places him as eleventh in line from Heracles. Scholarship has called Pheidon's 'reign' a tyranny based on Aristotle's definition in politics. Pheidon is said to have lost his life in a faction fight at Corinth, where the monarchy had recently been overthrown.
According to tradition he flourished during the first half of the 7th century BC. He was a vigorous and energetic ruler and greatly increased the power of Argos. He gradually regained sway over the various cities of the Argive confederacy, the members of which had become practically independent, and (in the words of Ephorus) reunited the broken fragments of the inheritance of Temenus. His object was to secure predominance for Argos in the north of Peloponnesus. According to Plutarch, he attempted to break the power of Corinth, by requesting the Corinthians to send him 1000 of their picked youths, ostensibly to aid him in war, his real intention being to put them to death; but the plot was revealed. Pheidon assisted the Pisatans to expel the Eleian superintendents of the Olympian Games and presided at the festival himself. The Eleians, however, refused to recognize the Olympiad or to include it in the register, and shortly afterwards, with the aid of the Spartans, who are said to have looked upon Pheidon as having ousted them from the headship of Greece, defeated Pheidon and were reinstated in the possession of Pisatis and their former privileges.
During his probable reign, the battle of Hysiae (in 669/8 BC) was fought in which the Argives defeated the Spartans. This is also about the time period that hoplite warfare was becoming current, particularly in Argos. It is probable that he was the originator of hoplite phalanx.
Aristotle, in "Politics", claims that he made changes to land reforms “family plots and the number of citizens should be kept equal, even if the citizens had all started with plots of unequal size.” He also claims that Pheidon started off as a king (basileus) and ended up a tyrant (tyrannos). The balance between these two types of ancient 'kingship' seem to have vague boundaries.
The affair of the games has an important bearing on his date. Pausanias (vi. 22, 2) definitely states that Pheidon presided at the festival in the 8th Olympiad (i.e. in 748 BC), but in the list of the suitors of Agariste, daughter of Cleisthenes of Sicyon, given by Herodotus, there occurs the name of Leokedes or Lakedas, son of Pheidon of Argos. According to this, Pheidon must have flourished during the early part of the 6th century BC. It has therefore been assumed that Herodotus confused two Pheidonscitation needed, both kings of Argos. The suggested substitution in the text of Pausanias of the 28th for the 8th Olympiad (i.e. 668 instead of 748) would not bring it into agreement with Herodotus, for even then, Pheidon's son could not have been a suitor in 570 for the hand of Agariste. But the story of Agariste's chronology. On the whole, modern authorities assign Pheidon to the first half of the 7th century.
Herodotus further states that Pheidon established a system of weights and measures throughout Peloponnesus, to which Ephorus and the Parian Chronicle add that he was the first to coin silver money, and that his mint was at Aegina. But according to the better authority of Herodotus (i. 94) and Xenophanes of Colophon, the Lydians were the first coiners of moneycitation needed at the beginning of the 7th century, and, further, the oldest known Aeginetan coins are of later date than Pheidoncitation needed. Hence, unless a later Pheidon is assumed, the statement of Ephorus must be considered unhistorical. No such difficulty occurs in regard to the weights and measures; it is generally agreed that a system was already in existence in the time of Pheidon, into which he introduced certain changes.citation needed
A passage in the Aristotelian Constitution of Athens states that the measures used before the Solonian period of reform were called Pheidonian. He mentions "a pheidon would be a jar of olive oil, named from the Pheidonian measures." It is mentioned that Solon reformed these measurements from the 70 drachmae of the Pheidonian coins to the 100 drachmae coins.