Decimatio in Practice

Only three decimations are attested prior to Crassus’ decimatio in 72 BC.Footnote ² The first was supposedly inflicted by Appius Claudius, the consul in 471 BC.Footnote ³ Following a defeat against the Volscians, Livy (2.59.11) claims that Claudius executed any soldier who returned to camp without weapons, any standard bearer who lost a standard, and any centurion who had deserted his post; he then decimated the mass of his defeated army. Dionysius (9.50.6–7) follows Livy in noting direct penalties for centurions and standard bearers, and decimatio for the rest, although he adds the detail that Claudius’ legates urged mercy, and that Claudius himself became an object of hatred (αὐτός τɛ μισούμɛνος) as he returned with his brutalised army. Frontinus (Str. 4.1.34) simply reports Claudius decimating those who fled their position by cudgelling, while Dio Cassius (at Zon. 7.17.5–7) suggests that Claudius was prosecuted as a result of the decimatio and committed suicide. There is every reason to believe that the episode has been slathered in ‘Clio's cosmetics’. However, it is entirely possible that Appius Claudius inflicted some sort of extraordinary punishment on his defeated soldiers, including executing some by lot, which became the basis for the subsequent construct of decimatio.

The next decimatio is assigned to Fabius Rullianus, active in the late fourth and early third centuries BC, who beheaded – not cudgelled – soldiers chosen by lot from two defeated legions. Frontinus (Str. 4.1.35), our only source, cannot provide a year or a location for this drastic action. The most plausible candidate would be Fabius’ defeat at Lautulae in 315 BC, although Frontinus himself does not make this connection. Still, it is entirely possible that Fabius inflicted the death penalty by lot on some soldiers who had fled in battle.

Finally, Frontinus (Str. 4.1.36) attributes an undated and unplaced event to an otherwise unknown general named Aquilius, who executed – again by beheading, not cudgelling – three men drawn by lot from each century that had been broken by the enemy, seemingly a modified decimatio (if centuries had a paper strength of 60 at this point, this would condemn one out of every 20 men). Morgan (Reference Morgan2003: 499) has compiled several Aquilii holding military commands: C. Aquilius Florus, cos. 259 BC, in Sicily, M'. Aquilius, cos. 129 BC, in Asia, and M'. Aquilius, cos. 101 BC, in Sicily. However, none of these men is known to have suffered a defeat. As for the last two, Plutarch (Crass. 10.2) indicates that Crassus’ decimatio in 72 BC was the revival of an ancestral penalty, lapsed ‘for a long time’ (διὰ πολλῶν χρόνων). While we need not think Plutarch is aiming for precision, this statement would be nonsensical if a prominent consul had decimated troops within living memory. Ultimately, the fact that Frontinus cannot give us so much as the precise identity of the general, let alone the historical context of the event, makes this supposed decimatio far more tenuous.

Nonetheless, it is likely that at least two, and perhaps three, commanders executed soldiers from defeated units by lot during the early Republic, less an established practice than an extraordinary – and extraordinarily rare – measure: over 150 years separated Appius Claudius from Fabius Rullianus. Yet these exceptional events (if they indeed occurred) inspired the creation of the rhetorical construct of decimatio as an established, regular punishment which commanders might routinely inflict at will on failed units. By the time detailed evidence for Roman military activity emerges, decimatio was a punishment that the Romans never used, a theory utterly without practice.

Absence of Evidence and Evidence of Absence

Ancient authors enjoyed recounting extreme and exemplary tales and were drawn to violent and dramatic events. The marked absence of attested decimations in the sources during the Middle Republic is therefore notable given that for the period from 218–167 BC we are remarkably well informed about military affairs. With the notable exception of Caesar's self-documented campaigns from 58–48 BC, this is probably the best attested period for the entirety of Roman military history from the monarchy to the Late Empire. In addition to Polybius and Livy, we also have Plutarch's lives of various Republican commanders, sundry exempla from the first century rhetorician Valerius Maximus, and the military treatise of Sextus Julius Frontinus (d. AD 103), Strategemata, a compilation of brief anecdotes derived and digested from historical sources.Footnote ⁴ Overall, Frontinus provides 46 incidents concerning discipline during the Republic. Frontinus had access to Livy's complete corpus, and so was in a position to inform us if the dramatic punishment was reported by Livy for the periods lost to us, 292–219 and after 167 BC (although, curiously, Frontinus does not describe the otherwise well-attested decimatio inflicted by Crassus).

Still, for all of this rich sourcing, we do not know of one datable instance of decimatio between Fabius Rullianus (probably 315 BC) and Crassus (72 BC). Of course, it is possible that a small-scale decimatio may have been performed on a single maniple or century without gaining the attention of our sources. Polybius reports the typical number of victims as rather low: five or eight or twenty. And yet, as discussed below, we know of many various lesser punishments meted out to centuries, maniples and cohorts for failure in battle, but never decimatio.

Goldberg (Reference Goldberg2015/16: 143–4) takes Polybius’ awareness of the punishment as proof that decimatio was routinely practised in the Middle Republic. And without question, Polybius is a worthy and well-informed source, and much of his information about the Roman army comes from either his own autopsy or well-placed oral informants, particularly his close friend Scipio Aemilianus. Polybius, however, often prefers generalised schematic analysis to specific observation, perhaps most famously in his discussion of the Roman constitution in Book 6.Footnote ⁵ While he includes decimatio as part of his theory as to why the Roman army works so well, he never once provides a specific instance of the punishment inflicted in the field during his extensive narrative of Roman military operations. Machado (Reference Machado2021: 389–97) has recently suggested that Polybius’ description of harsh Roman military discipline also serves his own ideological objectives, portraying the Romans as a people who took Greek organisational concepts to the extreme, but who also displayed a distinctive streak of barbarian violence.Footnote ⁶

The argument from silence becomes far more compelling when we consider that our sources record numerous instances of collective misconduct by Roman military units, and invariably report punishments other than decimatio. Below, I compile instances (see Table 1 for summary and citations) where Roman units displayed some form of collective ‘misbehaviour before the enemy’ to borrow a phrase of contemporary military law, and I note the punishment that was meted out.Footnote ⁷

1. 1. In the 270s BC, the Romans punished men who had surrendered to Pyrrhus and were subsequently repatriated by reducing their military status: equites were forced to serve as legionaries, and legionaries were forced to serve as light infantry.

2. 2. After the disaster at Cannae 216 BC, the survivors of the Battle of Cannae, roughly two legions worth of men, were collectively treated as scapegoats for the defeat. The punishment was a lengthy posting in Sicily, where many were still in service by 204 BC, at which point those still fit to serve were deployed with Scipio to Africa.

3. 3. In 214 BC, a legion of 4000 volunteer slaves (volones) under Sempronius Gracchus fought in a dilatory manner (segnius) and failed to join other units in storming the enemy camp. The slave-soldiers were sufficiently alarmed by their own poor performance that they took up a defensive position on a hill apart from the rest of the army, fearing harsh punishment. Instead, Gracchus announced the freedom of all of the volones (including a second legion that had performed well). He required the laggards to take their meals standing up as punishment, starting with a grand banquet thrown in Beneventum to celebrate the victory and manumission.

4. 4. In 210 BC, following Second Herdonia, a number of survivors, mostly Latins and Italians, were likewise sent to Sicily as reinforcements for the legiones Cannenses, remaining under arms until the end of the war.

5. 5. In 209 BC, Claudius Marcellus suffered a modest defeat at the hands of Hannibal, with a number of standards lost. Livy describes Marcellus angrily haranguing the defeated troops, who begged for forgiveness and promised to redeem themselves. Those maniples that lost standards were given barley rations. The centurions who commanded standard-less maniples were forced to stand guard overnight outside the praetorium. To add to their embarrassment and discomfiture, they were forbidden to wear either a cloak or a belt. If they were wearing mail shirts, the absence of the belt, which distributed the weight of the armour over the hips, would have made for an uncomfortable night, and also, as the passage notes, forced them to hold their swords in their hands. The chastised maniples contributed to a more successful engagement the following day.

6. 6. In 176 BC, the consul Q. Petilius was killed fighting the Ligurians, after what Livy describes as an otherwise successful battle.Footnote ⁸ Nonetheless, Frontinus and Valerius Maximus report that as a result of the consul's death the senate ordered the legion he was killed amongst to be marked as infrequens (i.e., AWOL), so that its stipendium from the past year was withheld and its pay going forward was reduced.

7. 7. In 143 BC, five cohorts in Spain gave way before the enemy. The consul, Caecilius Metellus Macedonicus, forced the soldiers to write wills, before sending them back into battle with the understanding that they would not be permitted to reenter the camp unless victorious. The enforced will writing seems to have represented both a humiliating ritual as well as a psychological exercise. The cohorts redeemed themselves with a win and were readmitted.

8. 8. In 133 BC, when an Italian cohort retreated before servile rebels in Sicily, the consul Lucius Piso ordered the cohort commander (praefectus cohortis) Gaius Titius to spend a day standing barefoot and unbelted by the praetorium (curiously Frontinus describes him as wearing a toga, perhaps a reference to some sort of surcoat). No collective punishment is mentioned for the cohort aside from the humiliation of its commander.

9. 9. Sulla at some point in his career ordered a cohort whose position had been overcome by the enemy, including its centurions, to stand in front of the headquarters wearing their helmets but without their belts. The punishment recalls that given to the centurions who had lost their standards previously during the Second Punic War, and to Gaius Titius, above, and indeed Frontinus groups the latter two anecdotes together. This seems to have been a relatively standard and enduring consequence for failed leaders, later utilised by Augustus (Suet. Aug. 24.2).

10. 10. In 71 BC, during Lucullus’ campaign against Mithridates, a detachment of Roman soldiers skirmished with a Pontic hunting party, with both sides committing additional troops. The Romans, however, were beaten back and fled. Lucullus personally rallied them to reform and repel the enemy. He punished the fugitives by forcing them to dig a 12-foot ditch, wearing only unbelted tunics, which Plutarch describes as a ‘customary punishment’ (ἀτιμία νɛνομισμένη).

Table 1

Collective misbehaviour in Roman Armies, 270s–71 BC

Not only do our sources fail to report any concrete incidents of decimatio, but we repeatedly encounter instances where maniples, cohorts, and even legions failed before the enemy but were given substantially more benign and inevitably non-lethal collective punishments. Humiliation and modest discomfort are a common theme: sentry duty without belts, eating standing up, and barley rations, the last of which Polybius assigns to the survivors of decimatio. While punishments are generally collective, commanders of failed units could be singled out for special humiliation. Notably, in no instance do we see violence: not only no executions, but no floggings either. These penalties were often inflicted with the hope of redemption, with the failed units encouraged to re-engage the enemy with greater success. This embodied the cultural trope of ‘triumph in defeat’ identified by Clark (Reference Clark2014), a reflex in which the Romans held that the failure and ignominy of military setbacks could be cleansed through eventual victory. Even the exile of the troops defeated at Cannae and Second Herdonia was premised on the notion that the defeated soldiers should serve until final victory was achieved; Scipio's decision to take the legiones Cannenses with him to Africa may have been in part pragmatic, as they were experienced troops, but also played into this ‘triumph in defeat’ narrative when they ultimately redeemed themselves at Zama (Livy, 29.24.13).

Not only do we utterly lack attestations for decimatio during a richly sourced period in Roman military history, we have numerous examples of units that would seem to have warranted it due to misbehaviour before the enemy and were instead consistently given far milder collective punishments. Rather than being a practical, routine punishment, decimatio seems to have been a civic myth during most of the Republic. As a myth, it served a social purpose, in constructing the authority of the aristocracy while illustrating the importance of battlefield courage and group solidarity. But prior to Crassus, it remained a myth.

Decimatio as a Construct

Roman aristocrats happily claimed the power to inflict decimatio, which they then did not use in practice, and we should ask why they eschewed this theoretical option. There is evidence of harsh punishments being directed at soldiers for other crimes. Desertion and defection were, unsurprisingly, dealt with savagely. Three hundred surviving members of the Campanian legion that had defected and seized Rhegium suffered mass execution at Rome in 270 BC.Footnote ⁹ Roman deserters variously had their hands cut off, were flogged and sold into slavery, or suffered mass execution when captured serving among the enemy.Footnote ¹⁰ This savagery was notably directed at men who on their own volition abandoned not just the res publica but also their comrades-in-arms; it is easy to imagine that these violent punishments were popular not only with aristocratic commanders but with the soldiers themselves too. Likewise, soldiers may have been happy to punish crimes like failure to keep watch, theft in camp, false witness, and sexual misconduct, acts which impacted their own community and quality of life, with fustuarium, themselves beating the offenders with cudgels (although Polybius admits, not always lethally).Footnote ¹¹ One difference between the relatively harsh punishments for these individual acts and the light punishments attested for collective failure in battle, was that a soldier had a conscious choice whether or not to desert to the enemy or steal in camp. But he might have no choice but to flee if his unit collapsed around him or an enemy assault proved unstoppable. Any Roman soldier must have known that he might become caught up in a retreat or rout, even if he personally preferred to stand firm and fight, and this fact might make savage punishments for collective failure far less popular and palatable than punishments for deserters and thieves.

Over the course of the second century BC a mix of law and custom seems to have further softened Roman discipline. A series of obscure laws, the leges Porciae, reaffirmed the right of provocatio against the arbitrary scourging and execution of citizens and extended it into the provincial sphere.Footnote ¹² Goldberg (Reference Goldberg2015/16: 154) suggests that these laws may have forbidden decimatio and other forms of execution, positing that Crassus and later generals simply ignored them in the authoritarian wake of Sulla's dictatorship. If Crassus had indeed decimated soldiers contrary to law, it is puzzling that we hear nothing of this from his many enemies. There was no suggestion that Crassus was vulnerable to the lex Clodia de civibus Romanis interemptis that sent Cicero into exile. It remains unclear to what extent the leges Porciae affected soldiers under oath at all, as opposed to civilians in the provinces.Footnote ¹³ Even so, laws can also generate norms, and even if the leges Porciae were narrow in their scope, legal emphasis on the rights of citizens abroad likely further stayed the hands of commanders. There is reason to believe that by the second century BC Roman commanders were holding back on flogging citizen troops with rods, while allied soldiers remained liable to such punishments.Footnote ¹⁴ This forbearance extended to executions: Sallust (Iug. 69.4) reports that in 108 BC, the prefect Titus Turpilius was flogged and executed for treachery, a severity attributed to his Latin status (nam is civis ex Latio erat).Footnote ¹⁵

The most important protection for Roman soldiers was ultimately not any statute, but rather the voting power of soldiers and their families more broadly. Roman commanders were elected officials who had to go back to Rome and face Roman voters. While the extent that the Roman Republic can be considered a democratic polity remains fiercely debated, it is clear that soldiers and their relatives were important and cultivated voting blocs for the aristocratic political class.Footnote ¹⁶ Cicero in the Late Republic could rhetorically ask,

Even on campaign, soldiers’ letters home could influence electoral politics (e.g., Sall. Iug. 65). The sources indicate that electoral pressures consistently mitigated the theoretically harsh discipline of the Roman army. Plutarch (Aem. 3.6, trans. Perrin Reference Perrin1918) praises Aemilius Paullus for οὐ δημαγωγῶν ἐν τῷ στρατηγɛῖν, οὐδ᾽, ὥσπɛρ οἱ πλɛῖστοι τότɛ, δɛυτέρας ἀρχὰς ταῖς πρώταις μνώμɛνος διὰ τοῦ χαρίζɛσθαι καὶ πρᾷος ɛἶναι τοῖς ἀρχομένοις (‘not courting popular favour when he was in command, nor yet, as most men did at this time, courting a second command during his first by gratifying his soldiers and treating them with mildness’). Praetorian commanders were most vulnerable to this dynamic: despite his conquest of Macedonia, Q. Metellus Macedonicus was repulsed in his first two consular campaigns, ‘despised by the plebs for his excessive severity’ (invisus plebi ob nimiam severitatem, [Aur. Vic.] De vir. Ill. 61.2), probably related to his discipline during the Fourth Macedonian War. Even the rare consul who did not see a future censor in the mirror still had to think how his political and military reputation impacted his family's political brand, as a bad reputation among soldiers and veterans could potentially threaten the prospects of his sons and other relatives.

Admittedly, Crassus did not seem to have been adversely affected by his decimatio, as he was elected consul shortly after the event. But the election of Pompey and Crassus was also a highly irregular one, uncontested by other candidates and undemocratic even by the standards of Roman elections.Footnote ¹⁷ It is quite likely that Roman participatory politics, as they functioned in the Middle Republic, played a major role in ameliorating aristocratic discipline, as a reputation for brutality or inequity towards citizen troops might easily prove a subsequent electoral liability.

And yet even as Republican-era commanders seem to have utterly lacked the confidence and will to inflict such a punishment, they insisted that they could. Why was Polybius informed by his sources that this punishment existed in the toolkit of the Roman imperator? The active claim to inflict such a punishment was very different from presenting the punishment as one that had existed once or twice in the distant past. As a rhetorical claim, the right to decimate failed units staked the theoretical nature of aristocratic powers markedly higher than what they dared effect in practice, but nonetheless constructed a vision, or at least a mirage, of aristocratic supremacy.Footnote ¹⁸ Indeed, these discourses may have been deployed by the nobiles to temper the popular pressures they faced and the temptation to get too close to their own troops. Roman aristocrats saw the practical and political benefit in eating the same food with their men, pointedly sharing hardships, and interacting with soldiers in a familiar way.Footnote ¹⁹ Such casual aristocratic Jovialität could easily be taken too far, and could interfere with the exercise of command.Footnote ²⁰ Worse, unconstrained familiarity might threaten the broader project of aristocratic solidarity; note the concern some senators evinced with Gaius Gracchus’ close connection to his army while serving as quaestor (Plut. C. Gracch. 2.3). A myth like decimatio was a means of generating psychological and social distance between aristocratic leaders and common followers, separated by the theoretical ability to inflict and suffer mass violence.

The supposed right to inflict a decimatio was also a negotiating position between elite commanders and the mass of soldiers. One of the paradoxes of military discipline is that commanders demanded submission and obedience from a group that was armed and organised and therefore capable of offering coordinated collective resistance to domination.Footnote ²¹ Indeed, in the case of the underperforming volones during the Second Punic War, we see that the disgraced soldiers, believing they would face punishment, assumed a defensive position before submitting to a mild sanction. Suetonius (Calig. 48.1–2) reports that when Caligula intended to decimate a legion in Germany on specious grounds, he was prevented from carrying out the procedure when the soldiers, who had been ordered to present themselves unarmed, managed to retrieve their weapons, forcing the emperor to flee ignominiously instead. The veracity of this anecdote is hardly beyond suspicion, but the story grapples with the obvious possibility that a military unit would not necessarily surrender itself to mass execution. Even for smaller units, less able to defend themselves, a commander's decision to administer a collective punishment required a degree of subtle negotiation between the commander, his council, and the broader mass of common soldiers.

Let us consider two examples of negotiated discipline, outside of decimatio. In 102 BC, a legion was defeated by the Cimbri.Footnote ²² Cut off by the Germans, the commanding tribune froze and was murdered by the primus pilus centurion, Gnaeus Petreius, who then managed a fighting withdrawal. In theory, savage punishment might be brought down upon Petreius for his remarkable act of homicidal insubordination. Petreius’ men, however, spontaneously awarded him the Grass Crown (corona graminea), which represented their negotiating position: the actions of the centurion and legion had been entirely honourable and necessary, worthy of celebration rather than punishment. The consuls ultimately accepted what was literally grassroots advocacy, as they later allowed Petreius to sacrifice in their presence.

We see a starkly different position in the response to a mutiny in Illyria in 75 BC by Gaius Curio (Frontin. Str. 4.1.43). One of his five legions mutinied, and Curio responded with a show of force: the other four were arrayed against the mutinous legion in battle formation, and the mutineers were disarmed and surrounded. Curio clearly felt the need to deploy overwhelming power as part of his negotiating position. But the punishment for which he summoned this display of strength was bloodless: the soldiers performed two days’ worth of fatigue duties, and then the legion was permanently disbanded, with the errant soldiers reassigned to the remaining four. Notably, despite Curio playing a very strong hand, the soldiers still tried to negotiate as he inflicted his administrative penalties, even if their pleas fell on deaf ears: ‘it was impossible to petition him with pleas from the legion’ (nullisque precibus legionis impetrari ab eo potuit).

Indeed, the history of decimatio after Crassus suggests that the revived punishment nonetheless largely remained a negotiating position. When the Ninth Legion mutinied at Placentia in 49 BC, Caesar threatened the entire legion with decimatio, which would have involved killing roughly 500 men. The threat prompted the soldiers to remonstrate, and Caesar softened his stance markedly; the legion was discharged and then re-enlisted, and 120 ringleaders were identified. Of these, 12 were executed by lot. Goldberg considers this a decimatio, and the ratio of 1/10 is indeed present, but it was not a decimatio after the description of Polybius, that is a punishment applied collectively to an entire unit regardless of individual behavior (Polybius also does not specify decimatio as a punishment for mutiny).Footnote ²³ Rather individuals were identified as culpable from across the unit, and then a fraction of those deemed guilty were punished.

Over the next two years, Caesar's soldiers themselves twice deployed decimatio as a negotiation ploy against their commander. In 48 BC, some of Caesar's defeated soldiers at Dyrrachium demanded decimatio; Caesar refused and instead had them swear oaths promising to regain a victory, which they subsequently did.Footnote ²⁴ In 47 BC, when the Tenth Legion joined a mutiny, Caesar threatened the unit with discharge and disbandment. The legion, long Caesar's favourite, instead requested decimatio as punishment. Caesar did not oblige, but rather reconciled with the legion and subsequently sailed with them to Africa.Footnote ²⁵ Similarly, Mark Antony, who inflicted a genuine decimatio on two cohorts during his Parthian campaign, shortly afterwards rejected an offer by his troops to submit to decimatio after another defeat, instead taking the blame upon himself (Plut. Ant. 44.3). In these instances, the soldiers’ request for a decimatio represented a gesture of fealty and submission (with the implicit demand for a lesser punishment or no punishment at all), and it was taken as such by commanders.

Reinvention and Abandonment

In 72 BC, decimatio, an archaic punishment in virtual desuetude for centuries (and perhaps never even used at all), was reinvented by Marcus Licinius Crassus to punish a legion that had performed poorly in the war against Spartacus. Plutarch (Crass. 2–3) reports that out of 500 men who fled in battle – a battle initiated by Crassus’ legate Mummius contrary to orders – 50 were executed. Appian (B Civ. 1. 118) gives two versions of the story, firstly that Crassus decimated two legions for defeats suffered under the prior consuls (which would produce a death toll of perhaps 1000 men) and alternatively that the decimatio took place after one of his own defeats, and that he decimated his entire army, killing 4000. The floating body count for this otherwise secure decimatio is a reminder about how such an event might be easily embellished. Plutarch's lower body count is to be preferred, but it is clear that Crassus suddenly manifested in practice what had long been an abstract discourse.

While subsequent decimations were inflicted under either democratically unaccountable military dynasts or emperors, Crassus was at this point far from being twice consul and triumvir. Although he had been a supporter and lieutenant of Sulla, at this point he was (probably) a mere praetor.Footnote ²⁶ We have no direct insight into Crassus’ motives, but three factors potentially underlie this grisly reinvention. Firstly, the Spartacus revolt had by this point devolved into a genuine emergency, having produced a string of military defeats and a host of defeated and disgraced units. The moral stigma of having been defeated by former slaves made these defeated units especially vulnerable to extraordinary punishments. Secondly, Crassus’ violence might be seen as an extension, and perhaps imitation, of Sulla's authoritarian style. Sulla's proscriptions of elite Romans and the massacre of thousands of citizen prisoners during the civil war quite likely weakened compunctions against using violence against citizens, not the least among his own acolytes: note that Verres’ crucifixion of a Roman citizen in Sicily occurred around the same time as Crassus’ decimatio.Footnote ²⁷

Finally, Crassus’ action took place against the background of an elite intellectual trend towards antiquarianism.Footnote ²⁸ The crescendo of antiquarian scholarship in the Late Republic has been linked to the rolling political crises of the period, and a yearning for more stable and legible times.Footnote ²⁹ Sulla's entire constitutional project was undergirded by antiquarian principles, including his revival of the long neglected title dictator, although as we have seen, Sulla's punishment of a cohort for cowardice, through non-lethal humiliation rather than decimatio, was in keeping with established Middle Republican practice. Crassus operated in a moment when antiquarian impulses were present in both warfare and politics. An inscription from Isaura Vetus from 75 BC reveals the Roman commander P. Servilius Vatia practised the otherwise obscure and seldom-used ritual of evocatio, mostly attested during the Roman conquest of Italy.Footnote ³⁰ The soon-to-be greatest of Roman antiquarians, M. Terrentius Varro, researched a study on Senate procedure that among other things considered the long defunct decemvirs and military tribunes with consular powers, supposedly as a handbook for Pompey, Crassus’ consular colleague in 70 BC (Gell. NA 14.7). We have no evidence directly linking Crassus personally to antiquarian research, but his deployment of a punishment not attested since the fourth century BC was well in keeping with the antiquarian trends of the period.

Crassus’ reinvention did not necessarily bring about a brisk return of the punishment, as decades passed before it was deployed again. Caesar's modified decimatio in 49 BC, which killed only 12 ringleaders in a mutinous legion, has already been discussed. Mark Antony may have also executed some mutinous soldiers at Brundisium by lot in 44 BC, although Appian explicitly specifies that he killed less than a tenth, and Cicero only describes the murder of centurions considered politically disloyal.Footnote ³¹ Notably, against modern assumptions that decimatio was an effective punishment, Appian (B Civ. 3.43) reports that this pseudo-decimation failed, as the soldiers, rather than being terrified and cowed, were only further angered: οἱ δὲ οὐκ ἐς φόβον μᾶλλον ἢ ἐς ὀργὴν ἀπὸ τοῦδɛ καὶ μῖσος ἐτρέποντο.

Dio Cassius (48.42.2) reports that in 39 BC, Domitius Calvinus, a proconsul in Spain and supporter of Octavian, decimated two centuries that had fled from an ambush, in addition to punishing a number of centurions, including a primus pilus. Velleius Paterculus (2.78.3), much closer to the event, only reports the fustuarium of the primus pilus for fleeing in battle (fusti percussit), and it is likely that Dio or his source mistook language describing the fustuarium for a more expansive decimatio.Footnote ³²

As discussed above, Antony decimated two cohorts after they were defeated by the Parthians in 36 BC (this would have involved killing roughly 80 men), but then subsequently refused to decimate his army after an even more serious defeat. Two years later, in 34 BC, Octavian decimated troops who had abandoned their positions in Illyria (Dio Cass. 49.38.3). Suetonius (Aug. 24.2) suggests that Augustus used decimatio as a routine punishment (cohortes, si quae cessissent loco, decimatas hordeo pavit), although no additional incidents are known, and it is possible he bases this statement upon the Illyrian incident alone.

Most attested decimations therefore took place between 49–34 BC, years of civil war, massive violence, and the rise of autocratic dynasts who were nonetheless plagued by the shifting and uncertain loyalties of their soldiers. Once the dust settled, decimatio quickly fell into disuse. The next attested incident comes over 50 years after Octavian in Illyria, when the legate Lucius Apronius decimated a cohort that had failed in Numidia against Tacfarinas during his tenure from AD 18–20 (Tac. Ann. 3.21). Another 50 years later, and in the context of another spasm of civil war, Galba decimated a legion that Nero had previously recruited from the navy when they refused to disband and return to the fleet.Footnote ³³ Thus, even when the punishment was re-established, decades and even generations passed without its effectuation. It may have gone into abeyance again during the High Empire, although the poor state of our sources makes it impossible to say this with confidence. Julian the Apostate may have decimated troops during his doomed campaign in Persia: Ammianus (24.3.2) describes him executing ten men from three cavalry turmae that had lost their standard, ‘following ancient laws’ (secutus veteres leges). If the incident was indeed a conscious decimatio, it would be the reinvention of a punishment not attested for nearly 300 years by an unusually erudite emperor.

In this paper I have argued that the popular mechanisms of the Roman Republic helped protect soldiers from what remained an aristocratic myth and negotiating position, so that no decimations were attested between 315–72 BC, even as many units failed in battle and received sub-lethal collective punishments. Such ‘democratic’ pressures did not apply to the Imperial period. The rarity of the punishment points to a more fundamental issue: decimatio was simultaneously so brutal and capricious that it failed utterly as a practical tool of military discipline.