The Sertorian War was a conflict of the Roman civil wars in which a coalition of Iberians and Romans fought against the representatives of the regime established by Sulla. It takes its name from Quintus Sertorius, the main leader of the opposition to Sulla. The war lasted from 80 BC to 72 BC. The war is notable for Sertorius' successful use of guerrilla warfare. The war ended after Sertorius was assassinated by Marcus Perperna who was then promptly defeated by Pompey.
Discontented Lusitanians decided to send envoys to Sertorius who at the time was in North Africa. The Lusitanians chose Sertorius because of the mild policy he had pursued while governor in 82 BC. The Lusitani had a long history of resistance to Rome. Some historians have concluded that the Lusitani were seeking independence and by taking over the leadership of the movement Sertorius was opposing Rome itself. Philip Spann considers this unlikely, as for Sertorius to accept such a treasonable offer would be to destroy any hope of returning to Rome. More likely the offer grew out of an acceptance by the Lusitani that they would not be able to defeat Rome and that their best hope was to assist the establishment in Rome of a regime sympathetic to them. Spann suggests that a major reason for Sertorius' acceptance was that it was becoming clearer that there would be no amnesty for him and his followers nor reconciliation with the regime set up by Sulla.
In 80 BC Sertorius, after defeating a naval force under Aurelius Cotta, landed in the Iberian Peninsula.Plutarch's account implies that Sertorius went first to Lusitania, organized the tribes and only then returned to the Baetis valley to defeat a Roman force. Spann suggests that a more probably sequence is that the Battle of the Baetis River occurred during Sertorius' initial march to Lusitania.
Concerned at the growing threat, the authorities in Rome appointed Quintus Caecilius Metellus Pius as governor of Hispania Ulterior. Metellus, basing himself at Metellinum (modern Medellin), made several thrusts into the interior, but was thwarted by Sertorius who used guerrilla tactics so effectively that after two years Metellus was exhausted. Meanwhile Sertorius' subordinate, Lucius Hirtuleius, was able to defeat Marcus Domitius Calvinus. In 77 BC he was joined by Perpenna who brought the remnant of the army of Marcus Aemilius Lepidus from Sardinia. However Perpenna had only reluctantly agreed to put himself under Sertorius' command; when his men had heard that Pompey had been sent to Iberia they had demanded that Perpenna join up with Sertorius.