The word decimate in the English language has come to mean to destroy or slaughter something but the word has an older historical meaning. The military context of the word can be traced back to the Romans, where the decimation of a military unit was a form of punishment and a way of enforcing military discipline. The word decimate comes from the Latin word decimare meaning to take or destroy one-tenth (from the Latin word decem meaning ten). For a Roman legion deemed to have failed in its duties this meant that one in ten legionnaires would be selected, stripped of their armour and beaten to death by their comrades. This would obviously kill one tenth and therefore decimate the offending legion. Marcus Licinius Crassus enforced an example of this during his campaign against the renegade gladiator Spartacus. Crassus’s legate Mummius engaged the rebel gladiators early, against Crassus’s wishes, and was defeated. 500 men of the legion involved were deemed to have shown cowardice and Crassus had one tenth killed - that is he decimated the legion to restore discipline. Strong parallels can be drawn between this action and those of the Soviet Union's commissars in World War 2 whose role was to install discipline and restore morale, often in a brutal fashion and frequently with the deaths of those thought to be showing cowardice.
The Complete Roman Army, Adrian Goldsworthy. A very good history of the Roman army from the early Republic to the end of the Empire.
How to cite this article:Dugdale-Pointon, T (20 December 2005) Decimate, http://www.historyofwar.org/articles/concepts_decimatel.html