Make your enemy work for you
In the modern world slavery is rejected as cruel and unacceptable. When thinking of slavery we vision pictures like here (more decently dressed of course than this Roman slave boy). One
should realize that slavery was first abolished when machines took over
the work from the slaves. In the ancient world slavery was accepted as normal. Jesus Christ, who objected against many abuses of his time, never spoke against slavery. Not even once. In early christianity masters were not encouraged to free their slaves. The only ones who didn't like slavery were the slaves them selves; until they were liberated or manumitted.
How to become a slave?
The most common way was: Being in a city that was conquered by the enemy.
After the conquest of a city there was a lot of looting, raping and killing. Who survived generally was sold as a slave.
Loosing a battle
Another way: Being part of an army and taken prisoner by the enemy. Often after a war the prisoners were sold back or it could be part of the peace treaty that the soldiers of the winning party
returned for free. After the battle of Cannae the Roman senate refused to buy the 10,000 prisoners from Hannibal.
Not paying your debts
Not being able to pay one's debts could also bring one into slavehood.
The debtor could try to make an agreement with his creditor to work his
debt off as a slave or he could be sold outside the city.
Someone could also sell himself or his children into slavery, e.g. he needed the money.
In 326 bc this form of slavery was banned..
Being sold by your father
A father could sell his children into slavery. This was seen as acceptable because somebody could be so poor that he couldn't feed his children properly. (There was no anticonception in those days.)
Children from slaves
Achild born out of a slave woman would become a slave, even if the
father was the owner of the slave or another free man. Children born by a free(d) woman were free. There were no
slave farms to breed slaves. In Rome, successful as it was in warfare,
there was no need to, since slaves kept pouring in from conquered
cities. This didn't mean slaves were cheap.
Lucky slaves
If a slave had desired qualities, like being literate, he or she could
have a good life. But it was also possible that someone with qualities
of a good fighter was made a gladiator.
Romans were quite generous in freeing slaves, who had done good work
for a long time (manumission). The
less fortunate had to work at a farm or in a mine,
Less lucky slaves
But the larger part of the slaves had to do unhealty jobs like working in the mines (where their life
expectation was 22 years at most) or at the large farmes of the Romans. Here on the right picture you see the basin of Stephano's laundery in Pompeii. Here new wool and dirty clothes were cleaned with urine. It were the slaves of course, who had to stamp around in the basin.
Here in this house at another place in Pompeii, now known as the Lupanara. Slave girls worked to please every man who payed for it.
(click to enlarge the pictures)