Summary: The eupatrids were the nobles who made up the cavalry and ruled ancient Athens. The rise of democracy in Athens came about when the value of the ordinary citizen as a soldier was finally recognized.
Society's Competing Needs for Protection and Food
Way back when there wasn't a draft and people didn't look to the military for a paycheck, although they may have seen it as an avenue to great wealth. Ancient cultures, including Athens, expected their wealthier citizens to serve as soldiers, providing their own horses, chariots, weapons and armors, and reaping rewards, if they won, through pillaging.
When ancient Athens needed more bodies for their military, they looked to ordinary citizen soldiers to augment the aristocracy's cavalry. These soldiers were small farmers barely able to stave off starvation for themselves and their families. Being required to serve in the military might provide plunder, but it would provide a hardship because the able bodies would be absent when they were most needed for agriculture.
Early Armies Manned By the Wealthy
As long as the military strength of a country depends on cavalry, the nobles and those with sufficient wealth to provide horses have a legitimate claim to power. After all, it's their lives and goods on the line. This was the case in Ancient Athens.
"And indeed the earliest form of constitution among the Greeks after the kingships consisted of those who were actually soldiers, the original form consisting of the cavalry for war had its strength and its pre-eminence in cavalry, since without orderly formation heavy-armed infantry is useless, and the sciences and systems dealing with tactics did not exist among the men of old times, so that their strength lay in their cavalry; but as the states grew and the wearers of heavy armor had become stronger, more persons came to have a part in the government."
Aristotle Politics 1297B
Need More Soldiers? Decrease the Qualifications
But with the rise of the hoplite, non-equestrian army, ordinary citizens of Athens could become valued members of society. For Athens, the hoplite warrior was not the poorest of the poor. Each hoplite had to have enough wealth to provide himself the requisite body armor to fight in the phalanx.
"Know that this is good for the city and for the whole people, when a man takes his place in the front line of fighters and keeps his position unflinchingly, has no thought at all of shameful flight, gives himself an enduring heart and soul, stands by his neighbour and speak words of encouragement to him: this is a good man in war."
Tyrtaeus Fr. 12 15-20
Rich vs Poor in Athens
By becoming a part of the hoplite phalanx, an ordinary citizen of Athens was demonstrably important. Along with his military importance came a sense that he had a right to be involved in decision-making processes. [See Four Tribes and the Ancient Social Order in Athens.] War meant the small farmer / ordinary citizen had to leave his farm, which could fail and his family starve unless a conclusion to the battle in which he was fighting was reached by the time he was needed to work his field. [See Land Shortage in Athens.] In addition, some of the aristocracy (known as eupatrids) became wealthier than ever because an economy based on exchange of commodities was replaced by coinage. The first clear sign of a new tension caused by the economy that developed between the eupatrids and the ordinary citizens was Cylon's attempt to usurp power in Athens....
Next Page: Cylon
Pericles of Athens and the Birth of Democracy, by Donald Kagan
The Greek City States: A Sourcebook, by P.J. Rhodes
The Rise of the Greeks, by Michael Grant
History of Greece to the Death of Alexander the Great, by J. B. Bury
Thomas Martin Overview of the History of Ancient Greece