|Base cost||10 Wealth|
|Creation time||Very fast|
|Line of sight||Poor|
|Created at|| Village|
|Prerequisites|| Meeting House:|
|Available to||All factions|
Slaves are an upgrade of Citizens (although sociologists can argue over whether this is morally desirable), costing Wealth rather than Food, and have no ramp cost and are trained much faster albeit being substantially weaker and slower than ordinary Citizens. Slaves can be recruited only if you have selected Offensive Doctrine as your Military policy and Patronage as your Civic policy at the Meeting House.
In Rise of Nations, Wealth is a very costly resource. Indeed, Wealth may well be harder to obtain than Food, given that it can be generated only by researching Taxation upgrades and/or building sufficient Markets and/or Wonders, so it would seem odd why anyone would want to create a worker-type unit which seems to be harder to create. The reason lies in two areas — the Slave's cost and training time. Unlike normal peasant units Slaves have no ramp and are easier to accumulate, Wealth willing. As long as you have sufficient Wealth, Slaves can be used to repair and consolidate newly taken cities from the enemy because they can be trained quickly. One Slave may well be worth three free Citizens because the same amount of resources that you may have used for a Citizen may allow you to purchase three Slaves, thus allowing you to quickly repopulate decimated areas in your realm.
So while it takes a while for Slaves to appear immediately in the game, those who can access them early on however will discover that they will have a very powerful advantage, having a cheap and reliable labour force in the late game. Slaves may also mean the difference between victory and failure in wonder-based strategies, since wonders take a long time and need many citizens in order to be created. Slaves, however, are weak and unlike normal Citizens in Rise of Nations cannot be armed, however they might be able to be used as a last resort to slow down enemy armies from taking your cities if need be, whether by garrisoning defensive positions or by going out to distract the enemy — their poor tactical stats do not permit them to be anything more than that. Moreover, once you obtain them, your economy and demographic growth are permanently dependent on Wealth, so should an enemy wipe out your empire and your trade, obtaining additional Slaves is going to be difficult as is attempting to repopulate your domain without ample Wealth in your coffers.
As such, slavery is not for everyone, although there are some factions which perform exceedingly well once they can access it. Slaves are a vital part of the Achaean League's economic strategy. Because the Achaean League can research Policies at the Meeting House for free, it only takes two clicks for them to research the two policies required to unlock the ability to "upgrade" all Citizens to Slaves. So for an Achaean player, Slaves can be very valuable indeed once a sufficiently high level in Civics or Commerce has been achieved because this then unlocks access to the market (required to sell resources for more Slaves) or the temple (to generate taxation income to purchase more), allowing for quick construction of a labour force to generate a massive army to crush the enemy. Other factions which might benefit well from Slaves also include factions with a wealth generation bonus like the Carthaginians, Lusitanians and Getae because of their greater access to wealth. Of these, the Lusitanians may have the best deal — Slaves recruited for mining eventually reproduce their worth in Wealth, and can even be killed off when no longer needed to remit part of their cost back to your coffers! On the other hand, slavery may prove to be a waste of time if you have other special bonuses. Because of the immense amounts of food they can produce as well as their ability to generate wealth from farms, the Egyptians are not advised to jump through the same political hoops as the Achaeans do just to obtain Slaves. This also applies to the Parthians whose ability to generate food quickly means that it is better to recruit Citizens to do their work. As for the Bactrians, the value of Slaves is even more moot given that they are expected to be able to create Citizens in a twinkling of an eye. It may be better to save up your Wealth for other projects as opposed to relying on Slaves to build up your economy, since the fast-producing peasants can get idle production buildings working in a jiffy.
The ancient Western world was notorious for its reliance on slavery as the mainstay of its economy (this was especially true of the Roman empire), the intensity and pervasiveness of which perhaps to a degree would surprise most modern people today. Slaves were not called as such originally: the word "slave" only came into existence during the Middle Ages. In ancient Greece, they were called douloi and in Latin servientes. The most common source of slaves was often through abduction or captivity through warfare, with the ongoing conflict between the Celtic tribes a major source of slaves for the Romans — prisoners of war captured in intertribal raids would be sent south to Rome in exchange for gold and wine.
To be a slave, however, wasn't always a bad thing. Contrary to popular perceptions of slavery coloured by the experiences of 19th century black Americans in the southern United States, slaves were not limited to just degrading "blue collar" tasks, but even manned banks, worked as salespersons and overseers, and even served as secretaries and teachers. Sometimes, slaves could earn property (which in Roman law was nominally considered their master's own), and a few even lived in security and comfort. Slaves sometimes became rich because they could apply their former work experience to their own business ventures if manumitted. One Athenian slave working as a clerk for bankers did so well at his tasks that he rose in rank, inherited the bank he was indentured to and ended his days as a remarkably wealthy freedman.
Overall however, it was not socially desirable to be a slave: they were normally bereft of all legal rights, were considered as the property of their masters and could be sold off or purchased. They could also be arbitrarily tortured or put to death although for some such treatment would have been seen as excessively destructive. The fate of slaves who displeased the Roman governor Vedius Polio (who fed them to a school of lampreys in his villa) underlines the extreme dangers slaves could expect to face in their economic and social bondage. The Emperor Augustus was so horrified at Vedius' cruelty that while he could not punish the governor personally, he had the lamprey pool filled in as a warning to others that such treatment was unacceptable. Augustus' measures were just one out of many measures implemented by Greek magistrates and Roman emperors to preserve social morality. Similar sentiments also made it a crime in Parthia to abuse a female slave. Eventually, however, heavy reliance on slave labour soon destroyed Roman society as the freeborn lower classes were eventually driven into poverty, creating a massive gap in legitimacy and wealth between the rich (as well as their slaves) and the poor, who crowded into city slums with no hope left of survival). Once this happened, the fate of Rome's agrarian economy in its western reaches was sealed, leading to various social and military pressures which soon destroyed the Empire as a going concern.