It is described by the Greek historian Polybius[2] in a passage observing that Roman soldiers were motivated to stand fast and maintain their posts by the fear of harsh punishments such as public disgrace, flogging, and death.
As a form of discipline imposed on a soldier, fustuarium thus reflected Roman doubts that courage alone was sufficient to ensure the steadfastness of the average soldier—an awareness that Julius Caesar shows in his war commentaries.
[8] All the behaviors punishable by the fustuarium—desertion, stealing, false witness, sexual misconduct and repeating three times a same offense—thus violate trust (fides) among fellow soldiers,[9] and the cudgeling was administered communally.
[10] Fustuarium was inflicted on a single soldier who committed an offense,[11] and thereby differs from decimatio, when a unit that had mutinied or disgraced itself by cowardice was compelled to randomly select every tenth man and stone, club or stab him to death by their own hands.
[13] Fustuarium may have originated as a religious rite of purification by means of which the unit purged itself through something like a scapegoat or pharmakos ritual.