Sertorius, QUINTUS, one of the ablest Roman commanders in the later ages of the Republic, was a native of Nursia, in the country of the Sabines. He began his military career in Gaul, and fought (105 B.C.) in the disastrous battle on the Rhone in which the Roman proconsul, Q. Servilius Cæpio, was defeated by the Cimbri and Teutones, and took part in the splendid victory at Aquæ Sextiæ or Aix (102 B.C.), where Marius annihilated the barbarians. On the breaking out of the sanguinary struggle between the party of the nobles under Sulla and the popular party headed by Marius (88 B.C.), he espoused the cause of the latter, though he could not respect Marius himself. For morally Sertorius was much superior to the military adventurers of his time; and the impression we have of him from Plutarch's picturesque biography is that of a valiant, resolute, honest, and stubborn Roman, such as was commoner in the 3d than in the 7th century of the Republic. None of the Marian generals held out so long or so successfully as he against the victorious oligarchy. He fought in conjunction with Cinna the battle at the Colline Gate, which placed Rome at the mercy of the Marians. But he took no active part in the bloody massacres that followed; on the contrary, he slew 4000 of Marius' cut-throat slaves who had committed the worst excesses. On the return of Sulla from the east (83 B.C.) Sertorius, finding it impossible to act in concert with the other military leaders of his party, went to Spain, where he continued the struggle in an independent fashion. At first he was unable to maintain his ground, and was obliged to put to sea. In the Mediterranean and in Morocco he led an adventurous life, sometimes fighting against the partisans of Sulla, sometimes mixing in the quarrels of native chiefs. But his fame grew, and at length he was invited back to Spain by the Lusitani; and from them and Roman refugees he formed troops who successfully defied the power of Rome for eight years or more. Sulla sent army after army against him commanded by such men as L. Domitius Ahenobarbus, Q. Metellus Pius, and young Pompey; but none of them was a match for him and his methods of guerilla warfare. The contest was at last terminated by the assassination of Sertorius in 72 B.C. The assassins were all Romans, men prescribed by Sulla, who were fighting under Sertorius. The chief of them was Perperna, who was jealous of his chief, and cherished ambitions of his own. Sertorius seems to have aimed at establishing a strong, stable government in Spain: he created a senate of 300 members from amongst the Romans of his party, and founded a school at Osca (Huesca) for the education of the sons of the Spanish chiefs.
But jealousies broke out between the Spaniards and the Romans, and the sternness of Sertorius changed to cruelty and tyranny. But when at the height of his power he was regarded with almost superstitious veneration by the Lusitanians, and the feeling was enhanced by the fact that the great commander was constantly followed about by a tame fawn.