The Sertorians comprised many Roman exiles from the Sullan proscriptions led by Sertorius, who fashioned himself proconsul, and native Celts, Aquitanians, and Iberians.

Sertorius consolidated control over both Hispanian provinces (Ulterior and Citerior) between 80–77 BC through pitched battles and guerrilla warfare, along with the aid of his legate Lucius Hirtuleius.

The Sullan generals were able to call on reinforcements from Rome, and from 74 BC onward conducted a war of attrition that the Sertorians were unable to stop.

In Tingis he was met by an embassy of discontented Lusitanians, a fierce Celtic people, who implored him to lead them against the Sullan government which was extorting them back home.

[5] 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.

[6] In 80 BC Sertorius, after defeating off Mellaria a small naval force under Aurelius Cotta, landed in the Iberian Peninsula at Baelo, near the Pillars of Hercules (Gibraltar).

[7] Plutarch's account implies that Sertorius first went to Lusitania, organized the tribes and only then returned to the Baetis valley to defeat a Roman force under Lucius Fufidius (probably the governor of Hispania Ulterior).

Spann suggests that a more probable sequence is that the battle of the Baetis River occurred during Sertorius' initial march to Lusitania.

While he consolidated his power in the south-west (Ulterior) he sent his trusted lieutenant, Lucius Hirtuleius, to Hispania Citerior to take care of its governor, one Cotta, and the remaining Sullan forces on the Iberian Peninsula.

[9] Concerned at the growing threat, the authorities in Rome upgraded Hispania Ulterior from a propraetorian to a proconsular province,[10] and appointed Quintus Caecilius Metellus Pius, Sulla's consular partner of 80 BC, as its governor.

[14] Metellus, unaware of the disaster, had already sent one of his legates, Lucius Thorius Balbus, to provide assistance to Domitius, but he too was defeated, this time by Sertorius himself.

[15] Metellus entered Spain in late 80 or early 79 BC, basing himself at Metellinum (modern Medellin), made several thrusts into the interior,[11] but was thwarted by Sertorius who used guerrilla tactics.

The light armour and consequent agility of his Iberian warriors meant Sertorius was constantly shifting the focus and changing the situation, until Metellus was at his wits' end.

Metellus was no longer young, and after the many heroic contests of his youth he was now inclined to ease and luxury, while Sertorius was full of mature vigour.

This strategy might have worked on an inferior opponent, but Sertorius kept up a relentless campaign of hit-and-run attacks and ambuscades slowly wearing down Metellus who was soon forced to call for help.

[22] In 77 BC Metellus adopted a more cautious strategy, only holding on to the line of the Baetis river while he awaited the events in Rome where a new revolt loomed.

[22] The ongoing Sertorian threat forced the government in Rome into taking drastic measures; they agreed that the new governor of Hispania Citerior should get a proconsular command and that he should be sent out with a sizeable army to support Metellus's struggle against Sertorius and his rebels.

In 76 BC the Senate accepted a proposal by Lucius Marcius Philippus to send his son-in-law Gnaeus Pompeius Magnus (Pompey), who had never been a magistrate, on behalf of the consuls (both of whom had refused the command themselves).

Pompey recruited an army of 30,000 infantry and 1,000 cavalry, its size evidence of the seriousness of the threat presented by Sertorius, and marched to Hispania.

Pompey also sent a fleet under his brother-in-law, Gaius Memmius, accompanied by the Spaniard Balbus, to try and take New Carthage, secure it as a base, and from there move up the coast.

[33] At the start of the campaigning season of 75 BC Pompey defeated Sertorius's legates, Perperna and Gaius Herennius, in a battle near Valentia.

They fought in the narrow space which separated the river from the city walls, conditions which favoured the battle hardened veterans of their opponent.

[35] Since his enemy remained drawn up in front of his camp for hours, Metellus had plenty of time to study their dispositions and make his own plans accordingly.

From my early youth I have endured peril and privation whilst the armies under my command put to flight the most criminal of your enemies and made you safe.

When I got tired of fruitlessly writing letters and sending envoys, I used up my personal resources, and even my credit, while in three years you have barely supplied me with enough to keep going for one.

The enemy [i.e. Perperna] were already at the throat of Italy, and I drove them from the Alps into Hispania, in the process opening for you a route far superior to Hannibal's.

Those parts of Hispania Citerior not held by the enemy are actually a costly burden for us because apart from the coastal towns both we and Sertorius have devastated it into total destitution.

While under most circumstances, any festivities to which Sertorius was invited were conducted with great propriety, this particular feast was vulgar, designed to offend the skillful general.

Perperna managed to retain control of some of the Roman renegades who had followed Sertorius, but he needed a quick victory to gain his people's trust.

[61] Perperna attempted to plead for his life, offering to give Pompey all of Sertorius' correspondence, which would document contacts with the highest levels of Roman government and society.