"The same goes for the Spartans. One-against-one, they are as good as anyone in the world. But when they fight in a body, they are the best of all. For though they are free men, they are not entirely free. They accept Law as their master. And they respect this master more than your subjects respect you. Whatever he commands, they do. And his command never changes: It forbids them to flee in battle, whatever the number of their foes. He requires them to stand firm -- to conquer or die." - From Herodotus' dialogue between Demaratos and Xerxes
In the eighth century B.C., Sparta needed more fertile land to support a booming population, so it decided to take over and use the fertile land of its neighbors, the Messenians. Inevitably, the result was war. The First Messenian War was fought between 700-680 or 690-670 B.C. At the end of twenty years of fighting, the Messenians lost their freedom and became agricultural laborers for the victorious Spartans. From then on the Messenians were known as helots.
Sparta - The Late Archaic City-State.
Helots of Messenia From Perseus' Thomas R. Martin, An Overview of Classical Greek History from Homer to Alexander
The Spartans took the rich land of their neighbors and made them helots, forced laborers. The helots were always looking for an opportunity to revolt and did in time revolt, but the Spartans won despite an overwhelming shortage of population.
Eventually the serf-like helots rebelled against their Spartan overlords, but by then the population problem in Sparta had been reversed:. By the time Sparta won the Second Messenian War (c. 640 B.C.), helots outnumbered Spartans by possibly as much as ten to one. Since the Spartans still wanted helots to do their work for them, the Soartan overlords had to devise a method of keeping them in check:
The Military State.
In Sparta, boys left their mothers at age 7 to live in barracks with other Spartan boys, for the next 13 years. They were under constant surveillance:
"In order that the boys might never lack a ruler even when the Warden was away, he gave authority to any citizen who chanced to be present to require them to do anything that he thought right, and to punish them for any misconduct. This had the effect of making the boys more respectful; in fact boys and men alike respect their rulers above everything. [2.11] And that a ruler might not be lacking to the boys even when no grown man happened to be present, he selected the keenest of the prefects, and gave to each the command of a division. And so at Sparta the boys are never without a ruler."
- From Xenophon Constitution of the Lacedaimonians 2.1
The state-controlled education [agoge] in Sparta was designed not to instill literacy, but fitness, obedience, and courage. Boys were taught survival skills, encouraged to steal what they needed without getting caught, and, under certain circumstances, to murder helots. At birth unfit boys would be killed. The weak continued to be weeded out, those who survived would know how to cope with inadequate food and clothing:
"After they were twelve years old, they were no longer allowed to wear any undergarments, they had one coat to serve them a year; their bodies were hard and dry, with but little acquaintance of baths and unguents; these human indulgences they were allowed only on some few particular days in the year. They lodged together in little bands upon beds made of the rushes which grew by the banks of the river Eurotas, which they were to break off with their hands with a knife; if it were winter, they mingled some thistle-down with their rushes, which it was thought had the property of giving warmth."
Separation from the family continued throughout their lives. As adults, men did not live with their wives, but ate at common mess halls with the other men of the syssitia. Marriage meant little more than clandestine dalliances. Even women weren't held to fidelity. Spartan men were expected to contribute a prescribed share of the provisions. If they failed, they were expelled from the syssitia and lost some of their Spartan citizenship rights.
Lycurgus - Obedience
From Xenophon Constitution of the Lacedaimonians 2.1
"[2.2] Lycurgus, on the contrary, instead of leaving each father to appoint a slave to act as tutor, gave the duty of controlling the boys to a member of the class from which the highest offices are filled, in fact to the "Warden" as he is called. He gave this person authority to gather the boys together, to take charge of them and to punish them severely in case of misconduct. He also assigned to him a staff of youths provided with whips to chastise them when necessary; and the result is that modesty and obedience are inseparable companions at Sparta."