Celtic slavery resembled that of ancient Greece and Rome. Slaves were acquired from war, raids, and penal and debt servitude. The word slave in Celtic languages was similar the Latin word for captive which may indicate the early origin of slaves. Slavery was hereditary, though manumission was possible. Manumissions were discouraged by law and the word cumal, meaning female slave, was used as a general unit of value in Ireland.
Slavery in Britain and Ireland dated from before Roman occupation. Parts of northern Britain and Scotland had large slave populations. Taken in war or raids the slaves were racially similar to their masters and were often integrated into the society. Some gained their freedom and became clients of their former masters as in Rome.
Anglo Saxons continued the system of slavery, often working with Norse traders who sold slaves to the Irish. They routinely exported slaves for trade. Dublin was a major slave trading center for centuries. St. Patrick was captured in England by Irish raiders and taken as a slave to Ireland. St. Brigit was the daughter of a Chritian Pictish slave.
In the Doomsday Book of 1086 about 10% of the English population were slaves. Legal penalties and economic pressures that led to default in payments maintained the supply of slaves, and in the 11th century there was still a slave trade operating out of Bristol. Chattel slavery gradually disappeared after the Norman Conquest to be replaced by the villeins who were tied to the land. In England, however, beggars could be enslaved until the middle of the 16th century. Tomorrow, The Vikings. Rita Bay