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In ancient Rome, commanders who broke the unwritten rules of military conduct might be greeted with either praise or punishment.

AS THE SUMMER OF 107 BCE DREW TO A CLOSE, Gaius Marius drove his legions deeper into the North African interior, determined to accomplish something great. A newly elected consul of the Roman Republic, he had recently taken command of Rome’s war against King Jugurtha, a canny foe whose Numidian kingdom sprawled across the north African coast in what today is Algeria. When Jugurtha refused to meet the legions head on in battle, preferring to use his mobile cavalry to raid and ambush rather than get chopped to bits by the Roman heavy infantry, Marius adopted the strategy of assaulting Numidian strongholds one by one.

Gaius Marius (Glyptothek München)

His latest target was the fortified town of Capsa, which reconnaissance revealed would be difficult to capture. Aside from its solid defenses, it was nestled in a sun-baked desert bereft of water, lacking forage, and reportedly infested with venomous snakes. None of this deterred Marius. He led his army in a series of daring marches until they arrived by night just a few kilometers outside Capsa. After concealing his forces in some hills, he watched and waited until the light of dawn began stretching over the horizon. The inhabitants of Capsa, utterly unaware of the legions lurking nearby, opened the gates to the town and went about their morning business. Marius saw his moment.

The Roman cavalry and light infantry sprang out of their hiding places and raced to the open gates, with Marius bringing up the rest of his army close behind. The people of Capsa immediately panicked as they saw the Romans barreling toward their open gates. Their leaders lost heart and surrendered before the wave of attacking legionaries crashed against their walls.

Despite the surrender, Marius did not restrain his men. In light of Capsa’s strategic importance, he thought the population could not be trusted and decided to neutralize the latent threat. His forces butchered the town’s adult males, rounded up women and children for sale into slavery, and then looted and torched Capsa.


THE ROMAN HISTORIAN SALLUST, WRITING IN THE FIRST CENTURY BCE, asserts that Marius committed an “act against the laws of war” by destroying Capsa after its people had surrendered. Yet the Romans did not have a concept of “war crimes” in a codified, legal sense. Nor did they invariably regard massacres, mass enslavement, or the destruction of entire towns and cities as beyond the pale. Indeed, Roman warfare was frequently punctuated by these and other large-scale atrocities, usually without comment or criticism in ancient texts. Such was common enough in the ancient world, when there were no effective international laws to curtail military violence and where victors enjoyed the “rights of conquest” over the vanquished—effectively the right to do whatever they wanted to defeated enemies.

On the other hand, the Romans did develop norms and conventions for the treatment of enemies who surrendered, and this is probably what Sallust means by “laws of war.” Notably, it was customary to spare enemies who submitted “before the ram touches the wall”—that is, who yielded without resisting. As the Roman historian Livy puts it, “towns are sacked after they are captured, not after they surrender.” These ideas were formalized in a Roman ritual of unconditional surrender called deditio in fidem, or “surrender to the good faith” of Rome. In this procedure, the surrendering party formally yielded its people, community, and property to Roman discretion. Polybius, a Greek author, observes that “the Romans gain possession of everything [in a deditio], and those who surrender remain in possession of absolutely nothing.” This may seem severe, and technically the ritual gave commanders license to do whatever they wanted. But the expectation—and the usual outcome—was that the Romans would treat the vanquished relatively well, perhaps imposing some minor punishment but then restoring their liberty and property.

Roman generals like Marius did not always follow these unwritten rules of conduct, however, and they were almost never punished for breaking them, as these were customs and conventions, not formal laws. Yet in the second century bce, three Roman commanders suffered severe political backlash when they treated surrendering enemies with abject ruthlessness. Their celebrated cases reveal that while the Romans took their military norms seriously, they ultimately failed to restrain gratuitous violence in war.

The first of these cases came in the summer of 189 bce, when the consul Fulvius Nobilior assaulted the Grecian city of Ambracia. Ambracia was a member of the Aetolian League, a confederation of communities at war with Rome; it was well-­fortified and strategically significant, so its capture would be a coup. Yet despite Nobilior’s tireless efforts to break through its defenses by using tunnels, siege engines, and towers, the Ambracians and their small Aetolian garrison bravely deflected every Roman attack. As exhaustion set in, the two sides entered negotiations. The Aetolian League made a separate peace with Rome, ending their war, while the Ambracians formally surrendered their city to Nobilior—who then let his soldiers thoroughly plunder the city.

On his way back to Rome a couple of years later, Nobilior planned to request a triumph for his accomplishments. (A triumph was a parade through Rome that celebrated a general’s glorious victories and reveled in the destruction of foreign foes; it was a great honor, only granted for outstanding military success.) But Marcus Aemilius Lepidus, one of Nobilior’s political opponents, saw an opportunity to turn sentiment against him. As Livy writes, Lepidus “introduced ambassadors from Ambracia into the Roman Senate, having suborned them to make accusations against Fulvius.” The Ambracian ambassadors bewailed that Nobilior had attacked them without just cause and sacked their city with utmost savagery. To add to their accusations, Lepidus forced the passage of a senatorial decree that ordered the return of the Ambracians’ looted property. Then he tacked on an additional clause stating that Ambracia had not been captured by force—suggesting that Nobilior had seized and sacked the city by less than glorious means.

Nobilior and his allies maintained that there was nothing unusual about the sack of Ambracia, since this sort of thing was commonplace when cities were captured in war. Moreover, they argued, Nobilior deserved a triumph for capturing Ambracia, since his soldiers had fought at the walls of the city for 15 days, inflicting 3,000 casualties on their resolute enemy. Most members of the Senate obviously agreed: In the end Fulvius got his triumph and openly paraded his well-won Ambracian loot to adoring Roman crowds.


SOME 16 YEARS AFTER NOBILIOR SACKED AMBRACIA, another Roman consul led his army against the Statellates, a Ligurian tribe in northwestern Italy. Although this particular tribe was not at war with Rome, its leaders drew up warriors for combat when they saw the legions approaching. The Roman commander, Popilius Laenas, was itching for a fight and, quickly throwing his own troops against the enemy’s, won the ensuing battle. When the Statellates surrendered afterward, Laenas took away their weapons, sacked their main town, and sold them all into slavery.

Laenas proudly reported all of this to the Roman Senate, apparently expecting praise for a job well done. Instead, many senators were appalled: He had attacked the only Ligurian tribe still at peace with Rome and then enslaved its people after their formal surrender; this was not only harmful to Rome’s reputation but strategically unwise, since it set a bad precedent for other communities that might surrender in the future. The Senate ordered Laenas to free the enslaved Statellates and restore their property. Infuriated, he instead returned to the capital to object. As far as he was concerned, the Senate should have decreed honors to the immortal gods for the successes he had enjoyed in war. The Senate then ordered another consul to liberate the Statellates and resettle them farther south. The senators also supported the creation of a special court to prosecute Laenas for his misdeeds, but this came to nothing. In 159 bce Laenas was even elected to the prestigious office of censor. Any ill will against him presumably must have faded away.


FINALLY, IN 150 BCE, A PAIR OF ROMAN COMMANDERS led a two-pronged invasion into western Spain and systematically ravaged the landscape. They were determined to suppress the Lusitanians, a tribe that had been launching regular raids into Roman territory and had humiliatingly defeated several Roman armies. Their punishing counterattack worked: Several Lusitanian communities approached Sulpicius Galba, one of the Roman generals, and formally surrendered. At first Galba received them kindly, made a truce, and pretended to be sympathetic to their plight. “It is your poor soil and your poverty that compels you to [raid and make war],” he told them, according to the Greek historian Appian. “I will give my needy friends good land, dividing them into three sections and settling you in a bountiful country.” Galba then led the Lusitanians to three different locations with the promise of resettlement, where his troops disarmed them, surrounded them, and massacred all men of military age. They sold the women and children.

If Galba expected a hero’s welcome in Rome for suppressing the Lusitanians, he was sorely disappointed. In a series of public meetings, several senators denounced him for violating the “good faith” of Rome. Among his accusers was Marcus Cato the Elder, a leading statesman, a bitter rival, and a famously effective speaker. One Roman official also proposed a bill that would not only have sought out and freed the enslaved Lusitanian survivors but also put Galba on trial in a special criminal court. Yet Galba was an accomplished orator himself, and he delivered three speeches in his own defense, in which he claimed that the massacre was preemptive because the Lusitanians were planning to attack his army and had only pretended to make a truce to hide their real plans. Galba later appeared before the citizenry with his children in tow, tearfully entrusting the youths to the guardianship of the Roman people; after all, they would soon become orphans if he were condemned in court.

Roman voters rejected the proposals arrayed against Galba, so there was no special trial and no remediation for the survivors of his massacre. His pragmatic justification for violence and pitiful histrionics were apparently more persuasive than norms or ethical principles with respect to the treatment of enemies. In fact, Galba went on to hold the consulship, Rome’s highest elected office, a few years later. Evidently the Romans decided that his atrocity was acceptable, or at least forgivable.

There was an epilogue to this story, albeit an unimpressive one. The same year that Galba escaped trial, the Romans passed a law called the Lex Calpurnia. The law instituted a permanent court designed to prosecute the misbehavior of Roman officials operating abroad. Several scholars argue that this new court was a direct response to Galba’s case and an effort to prevent similar atrocities in the future. But if so, the new courts were a weak remedy, as they were solely concerned with the restoration of property and offered no restitution for massacre, enslavement, or other such sufferings.


FOR SOME LEADING ROMANS, VIOLATIONS OF MILITARY CUSTOM WERE SERIOUS OFFENSES. Otherwise there would have been no grounds for complaint against Galba, Laenas, and Nobilior, and no audience willing to hear the accusations against them. Nonetheless, their stories show that Rome’s “surrender norms” were a poor source of restraint in war. On the one hand, the mistreatment of surrendered enemies could inspire public outrage and could be weaponized by political rivals. Galba and Laenas were even threatened with formal trials, which might have ruined their political careers, or worse. On the other hand, none of these men thought they had done anything wrong—Laenas and Nobilior even expected reward—and none were punished. All went on to enjoy future political success.

In the end, the three cases illustrate the inherent flexibility of military ethics in Rome and elsewhere: Breaches of norms only become “criminal” if there is a way, and a willingness, to punish offenders. MHQ

Gabriel Baker is a historian who specializes in mass violence and atrocity in ancient warfare.


This article appears in the Summer 2020 issue (Vol. 32, No. 4) of MHQ—The Quarterly Journal of Military History with the headline: Laws of War | Crimes and Consequence

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