(2) Polybius, The Rise of the Roman Empire (c. 110 BC)
If the Roman soldier is found guilty (of falling asleep on duty), he is punished by fustuarium. This is carried out as follows. The tribune takes a cudgel and lightly touches the condemned man with it, whereupon all the soldiers fall upon him with clubs and stones, and usually kill him...
If large groups desert their posts under extreme pressure, the officers reject the idea of beating to death or executing all who are guilty, but the solution they adopt is as effective as it is terrifying. The tribune calls the legion on parade... he chooses by lot... about a tenth of those who have shown themselves guilty of cowardice. Those on whom the lot has fallen are clubbed to death.
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The killing of the tenth of the soldiers was the original meaning of “decimate”. Modern usage of decimate has changed to mean completely destroyed.
Pilate told the Jewish priests that it was their problem, not his, and to use their own guards, which means that Pilate was not concerned w/ them or what happened.
The priests, on the other hand, had much to lose if the guarded tomb was empty, so they paid the soldiers to go with the “I fell asleep” story (which is implausible, but which met the immediate purpose of the priests).
Since the soldiers didn’t violate Pilate’s command, they weren’t under his authority on the matter, i.e. no decimation (which, btw, begs the matter if there were only a few guards... decimate a limb?)