(Οὐιρίαθος Diod. and Dio Cass. : Οὐρίατθος, Appian), a Lusitanian, commanded his countrymen in their war against the Romans, whose power he defied, and whose armies he vanquished during many successive years. He is described by the Romans as originally a shepherd or huntsman, and afterwards a robber, or, as would be called in Spain in the present day, a guerilla chief. His character is drawn very favourably in a fragment of Dio Cassius (Fragm. 78, p. 33, ed. Reimar.), and his account is confirmed by the testimony of other ancient writers, who celebrate especially his justice and equity, which was particularly shown in the fair division of the spoils he obtained from the enemy. (Comp. Diod. vol. p. 519, ed. Wess.; Cic. de Off. 2.11.) The Lusitanians had long been accustomed to support themselves by robbery and rapine; and as they still continued their predatory mode of life after the Romans had become masters of the neighbouring countries, the Roman commanders in Spain resolved to reduce them to submission. Accordingly in B. C. 151 their country was invaded by the propractor Ser. Galba, and in the following year (B. C. 1.50) by the proconsul L. Lucullus as well as by Galba. The Lusitanians in alarm sent offers of submission to Galba, who enticed them to leave their mountain fastnesses by promising to give them fertile lands, and when they had descended into the plains, relying on the word of a Roman general, he surrounded them with his troops and treacherously butchered them. Very few of the Lusitanians escaped, but among the survivors was Viriathus, who was destined to be the avenger of his country's wrongs The Lusitanians, who had not left their homes, rose as a man against the rule of such treacherous tyrants, and they found in Viriathus a leader who was well acquainted with the country, and who knew how to carry on the war in the way best adapted to the nature of the country and the habits of his countrymen. At first he avoided all battles in the plains, and waged an incessant guerilla warfare in the mountains. It was not, however, till B. C. 147 that the Lusitanians were able to collect any formidable body of men; and in this year having invaded Turdetania, they were attacked, while ravaging the country, by the Roman propraetor C. or M. Vetilius, defeated with loss and obliged to take refuge in a fortress, to which the Romans laid siege. The want of provisions prevented them from holding out long, and they accordingly endeavoured to make terms with Vetilius, who promised to assign to them a place where they might settle. Viriathus, who was serving among his countrymen, but who had not yet been formally recognised as their general, reminded them of the treachery of the Romans, and promised, if they would obey his commands, to save them from their present danger. His offer was gladly accepted, and he was unanimously elected their commander. By a bold and skilful stratagem he eluded the Roman general, and again assembled his forces at Tribola, a town to the south of the Tagus in Lusitania. Thither he was followed by Vetilius; but Viriathus, pretending to retreat, led the Romans into an ambuscade, where they were attacked by the Lusitanians, and defeated with great loss : Vetilius himself was killed; and out of 10,000 Romans scarcely 6000 escaped. The survivors took refuge under the command of the quaestor within the walls of Carpessus, which Appian supposes to be the same as the ancient Tartessus. Fearing to meet the enemy in the field, the quaestor obtained 5000 men from the Belli and Titthi, Celtiberian tribes, who were then allies of the Romans, and sent them against Viriathus; but they were also defeated by the Lusitanian general, who now laid waste Carpetania without encountering any opposition.

On the arrival of the praetor C. Plautius in the following year, B. C. 146, with a fresh army, Viriathus abandoned Carpetania and retreated into Lusitania. He was eagerly followed by Plautius, who crossed the Tagus in pursuit of him, but while the Romans were engaged in fortifying their camp on a mountain, covered with olives, which the Roman writers call the Hill of Venus, they were attacked by Viriathus and put to the rout with great slaughter. Plautius was so disheartened with this defeat that he made no further attempt against the enemy, but led his army into winter quarters, although it was still only the middle of summer. The country of the Roman allies was thus again left exposed to the ravages of Viriathus, who compelled the inhabitants to pay to him the full value of their crops, and destroyed them if they refused. He also took Segobriga, the chief town of the Celtiberians. (Frontin. Strat. 3.11.4.)

The war in Spain had now assumed such a threatening aspect that the senate resolved to send a consul and a consular army into that country. Accordingly, in B. C. 145, the consul Q. Fabius Aemilianus, the son of Aemilius Paulus, who conquered Macedonia, received Spain as his province. He levied two new legions at Rome, consisting for the most part of new recruits, in order to give some repose to the veteran troops, who were worn out by the wars in Greece and Macedonia. He likewise obtained some forces from the allies; and when he mustered his troops at Urso or Orso, the modern town of Osuna in Andalusia, his army amounted to 15,000 foot and 2000 horse. But before his arrival in Spain the Romans had again experienced another disaster. The army of the praetor Claudius Unimanus had been nearly annihilated, and the fasces and other spoils taken from the Romans had been erected by Viriathus as trophies in the mountains. (Flor. 2.17.16.) Fabius appears not to have arrived in Spain till the middle of the summer; and as he would not fight with the enemy till his raw troops had received further training, he left his army under the command of his legate, while he himself went over to Glades to offer a sacrifice to Hercules. In his absence his foragers were attacked by Viriathus, who slew many of them; and the legate of Fabius having thereupon ventured to offer battle to Viriathus, was defeated. When Fabius returned from Gades, he could not be tempted by Viriathus to any regular engagement, but passed the remainder of the year in exercising his troops and in occasional skirmishes with the enemy, by which his soldiers acquired confidence and experience. In the following year (B. C. 144) Fabius was continued in the government of Spain, and he now felt sufficient reliance upon his troops to venture to attack Viriathus with all his forces. Viriathus was defeated and driven out of the Roman dominions in Spain, and his two chief towns fell into the hands of Fabius. After these successes Fabius led his troops into winter quarters at Corduba.

These successes of Fabius, however, were more than counterbalanced by another formidable insurrection in Spain. The Arevaci, Belli, and Titthi, Celtiberian people, inhabiting that part of Spain now called Old Castile, had been subdued by the Romans some years previously, and two of them, the Belli and Titthi, had, as we have already seen, sent assistance to the Romans in their war against Viriathus. They were now, however, induced to follow the example of Viriathus, and to take up arms against the Romans, and thus almost the whole of central Spain was in open revolt. The war against the Celtiberians became even more protracted than that against the Lusitanians, and is usually known by the name of the Numantine war, from Numantia, the principal town of the Arevaci.

In B. C. 143 the consul Q. Metellus Macedonicus was sent into Nearer Spain, and the propraetor Q. Pompeius into Further Spain, as the successor of Fabius Aemilianus. * Appian, App. Hisp. 66, calls the successor of Fabius Quintius ; but by this name he must understand Quintus Pompeius : see Drumann, Geschichle Roms, vol. iv. p. 307. While Metellus conducted the war with success against the Celtiberians, Pompeius was not equally fortunate in his campaign against Viriathus. He had at first gained a victory over the Lusitanian general, and pursued him as far as the mountain south of the Tagus, which has been already mentioned under the name of the Hill of Venus. Here Viriathus turned upon his pursuers, and drove them back into their camp with the loss of 1000 men and several standards. This defeat so disheartened Pompeius that he allowed the enemy to lay waste the country around the Guadalquiver without resistance, and led his army early in the autumn into winter-quarters at Corduba.

In the following year, B. C. 142, the consul Q. Fabius Servilianus was sent into Further Spain as the successor of Pompeius. Q. Metellus remained as proconsul in Nearer Spain. Servilianus brought with him two Roman legions and allied troops, amounting in all to 16,000 foot and 1600 horse, and he also obtained from Micipsa some elephants. He at first carried on the war with great success, defeated Viriathus, and compelled him to retire into Lusitania, took by storm many of his cities, and exterminated several guerilla bands. Next year, however, B. C. 141, when Servilianus remained in Spain as proconsul, the fortune of war changed. The Romans had laid siege to Erisane; Viriathus stole into the town by night, and at the dawn of day made a successful sally against the besiegers. The Romans lost a great number of men, and were put to flight. In their retreat they became enclosed within a mountain pass, where they were surrounded by the Lusitanians, much in the same way as their ancestors had been by the Samnites at the celebrated Caudine Forks. Escape was impossible, and they had no alternative but an unconditional surrender. Viriathus used his victory with moderation. He agreed to allow the Romans to depart uninjured, on condition of their permitting the Lusitanians to retain undisturbed possession of their own territory, and of their recognising him as a friend and ally of the Roman people. Servilianus concluded a treaty with Viriathus on these terms, and it was ratified by the Roman people.

Thus the war with Viriathus appeared to have been brought to a conclusion; but the consul Q. Servilius Caepio, who succeeded his brother Servilianus in the command of Further Spain in B. C. 140, was greatly disappointed at the unexpected termination of the war. He had looked forward to the war in Spain as an opportunity for gaining both wealth and glory; and he therefore used every exertion to induce the senate to break the treaty by representing it as unworthy of the Roman people. The senate, however, had not the effrontery to give their approval to an open violation of the peace. but connived at Caepio's injuring Viriathus as far as he could without any open attack. But after a short time we are told that the senate allowed Caepio to declare open war against Viriathus, probably having obtained meantime some pretext for this act of faithlessness. Caepio forthwith took the field against Viriathus; but the latter sent three of his most faithful friends, Audax, Ditalco, and Minurus, to the Roman general, to offer him terms of peace. Caepio persuaded the envoys by promises of large rewards to murder Viriathus. Accordingly, on their return they murdered Viriathus, while he was asleep in his tent, and made their escape to the Roman camp before any of the Lusitanians became aware of the death of their general. The murderers, however, did not receive the rewards which had been promised them; and when they demanded them of the consul, he coolly replied that the Romans did not approve of the murder of a general by his own soldiers. The death of Viriathus did not put an immediate stop to the war. After burying Viriathus with great magnificence, his soldiers elected Tantalus as their general ; but the latter was no match for a Roman consul, and before the end of the year was obliged to submit to Caepio. [CAEPIO, No. 6.] The war with Viriathus lasted eight years, according to Appian (App. Hisp. 75), who dates its commencement from the time that Viriathus became the leader of the Lusitanians. Other writers, however, say that the war lasted fourteen years, which must be computed from the beginning of the Celtiberian war, B. C. 153. (Appian, App. Hisp. 60_75; Eutrop. 4.16; Oros. 5.4; Flor. 2.17; Liv. Epit. 54 ; Frontin. 2.5.7, 2.13.4, 3.10.6, 3.11.4, 4.5.22; Vell. 2.1; Aurel. Vict. de Vir. Ill. 71; V. Max. 9.6.4; Diod. Exc. ex xxxii. pp. 591, 597, ed. Wess.; Dio Cass. Fragm. 78, p. 33, ed. Reimar.)