Extraordinary successes in northern and in southern Spain marked the next years of his generalship. After destroying the vanguard of the praetor Gaius Plautius (608-9), Viriathus had the skill to lure him over to the right bank of the Tagus, and there to defeat him so emphatically that the Roman general went into winter quarters in the middle of summer--on which account he was afterwards charged before the people with having disgraced the Roman community, and was compelled to live in exile. In like manner the army of the governor-- apparently of the Hither province--Claudius Unimanus was destroyed, that of Gaius Negidius was vanquished, and the level country was pillaged far and wide. Trophies of victory, decorated with the insignia of the Roman governors and the arms of the legions, were erected on the Spanish mountains; people at Rome heard with shame and consternation of the victories of the barbarian king. The conduct of the Spanish war was now committed to a trustworthy officer, the consul Quintus Fabius Maximus Aemilianus, the second son of the victor of Pydna (609). But the Romans no longer ventured to send the experienced veterans, who bad just returned from Macedonia and Asia, forth anew tothe detested Spanish war; the two legions, which Maximus brought with him, were new levies and scarcely more to be trusted than the old utterly demoralized Spanish army. After the first conflicts had again issued favourably for the Lusitanians, the prudent general kept together his troops for the remainder of the year in the camp at Urso (Osuna, south-east from Seville) without accepting the enemy's offer of battle, and only took the field afresh in the following year (610), after his troops had by petty warfare become qualified for fighting; he was then enabled to maintain the superiority, and after successful feats of arms went into winter quarters at Corduba. But when the cowardly and incapable praetor Quinctius took the command in room of Maximus, the Romans again suffered defeat after defeat, and their general in the middle of summer shut himself up in Corduba, while the bands of Viriathus overran the southern province (611).
His successor, Quintus Fabius Maximus Servilianus, the adopted brother of Maximus Aemilianus, sent to the peninsula with two fresh legions and ten elephants, endeavoured to penetrate into the Lusitanian country, but after a series of indecisive conflicts and an assault on the Roman camp, which was with difficulty repulsed, found himself compelled to retreat to the Roman territory. Viriathus followed him into the province, but as his troops after the wont of Spanish insurrectionary armies suddenly melted away, he was obliged to return to Lusitania (612). Next year (613) Servilianus resumed the offensive, traversed the districts on the Baetis and Anas, and then advancing into Lusitania occupied a number of townships. A large number of the insurgents fell into his hands; the leaders--of whom there were about 500--were executed; those who had gone over from Roman territory to the enemy had their hands cut off; the remaining mass were sold into slavery. But on this occasion also the Spanish war proved true to its fickle and capricious character. After all these successes the Roman army was attacked by Viriathus while it was besieging Erisane, defeated, and driven to a rock where it was wholly in the power of the enemy. Viriathus, however, was content, like the Samnite general formerly at the Caudine passes, to conclude a peace with Servilianus, in which the community of the Lusitanians was recognized as sovereign and Viriathus acknowledged as its king. The power of the Romans had not risen more than the national sense of honour had sunk; in the capital men were glad to be rid of the irksome war, and the senate and people ratified the treaty. But Quintus Servilius Caepio, the full brother of Servilianus and his successor in office, was far from satisfied with this complaisance; and the senate was weak enough at first to authorize the consul to undertake secret machinations against Viriathus, and then to view at least with indulgence the open breach of his pledged word for which there was no palliation. So Caepio invaded Lusitania, and traversed the land as far as the territories of the Vettones and Callaeci; Viriathus declined a conflict with the superior force, and by dexterous movements evaded his antagonist (614). But when in the ensuing year (615) Caepio renewed the attack, and in addition the army, which had in The meantime become available in the northern province, made its appearance under Marcus Popillius in Lusitania, Viriathus sued for peace on any terms. He was required to give up to the Romans all who had passed over to him from the Roman territory, amongst whom was his own father-in-law; he did so, and the Romans ordered them to be executed or to have their hands cut off. But this was not sufficient; the Romans were not in the habit of announcing to the vanquished all at once their destined fate.
One behest after another was issued to the Lusitanians, each successive demand more intolerable than its predecessors; and at length they were required even to surrender their arms. Then Viriathus recollected the fate of his countrymen whom Galba had caused to be disarmed, and grasped his sword afresh. But it was too late. His wavering had sown the seeds of treachery among those who were immediately around him; three of his confidants, Audas, Ditalco, and Minucius from Urso, despairing of the possibility of renewed victory, procured from the king permission once more to enter into negotiations for peace with Caepio, and employed it for the purpose of selling the life of the Lusitanian hero to the foreigners in return for the assurance of personal amnesty and further rewards. On their return to the camp they assured the king of the favourable issue of their negotiations, and in the following night stabbed him while asleep in his tent. The Lusitanians honoured the illustrious chief by an unparalleled funeral solemnity at which two hundred pairs of champions fought in the funeral games; and still more highly by the fact, that they did not renounce the struggle, but nominated Tautamus as their commander- in-chief in room of the fallen hero.