Decimation (Roman army)

Decimation (Latin: decimatio; decem = "ten") was a form of military discipline used by senior commanders in the Roman Army to punish units or large groups guilty of capital offences, such as mutiny or desertion. The word decimation is derived from Latin meaning "removal of a tenth". The procedure was a pragmatic attempt to balance the need to punish serious offences with the realities of managing a large group of offenders.

A cohort (roughly 480 soldiers) selected for punishment by decimation was divided into groups of ten. Each group drew lots (sortition), and the soldier on whom the lot fell was executed by his nine comrades, often by stoning or clubbing. The remaining soldiers were often given rations of barley instead of wheat (the latter being the standard soldier's diet) for a few days, and required to camp outside the fortified security of the camp.

Because the punishment fell by lot, all soldiers in a group sentenced to decimation were potentially liable for execution, regardless of individual degrees of fault, rank, or distinction.

The earliest documented decimation occurred in 471 BC during the Roman Republic's early wars against the Volsci and is recorded by Livy. In an incident where his army had been scattered, consul Appius Claudius Sabinus Regillensis had the culprits punished for desertion: centurions, standard-bearers and soldiers who had cast away their weapons were individually scourged and beheaded, while of the remainder, one in ten were chosen by lot and executed.

Polybius gives one of the first descriptions of the practice in the early 3rd century BC:

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