,
Spain|thumb|240px Sometime during his consulship,
Quintus Sertorius, an opponent of Sulla, established himself in Hispania and began a rebellion against the Senate. In 80 BC, after Sertorius had defeated Lucius Fufidius, the governor of
Hispania Ulterior, the Senate decided to send Metellus once his term as consul had ended. Upgrading Hispania Ulterior to a consular
province, they dispatched Metellus to take charge of the war against Sertorius. Arriving in Hispania in 79 BC Metellus established his bases at
Metellinum (today
Medellín),
Castra Caecilia (today
Cáceres),
Viccus Caecilius, at the
Sierra de Gredos, and at
Caeciliana, near
Setúbal. From the start, it was clear that Metellus was outclassed by the brilliant Sertorius suffering repeated defeats through Sertorius’ use of guerrilla tactics. His
legate Thorius (probably Lucius Thorius Balbus) −dispatched to come to the assistance of the governor of
Hispania Citerior,
Marcus Domitius Calvinus− was defeated by Sertorius (79 BC). After Thorius's defeat Metellus decided to take on Sertorius himself. Metellus was a solid if unspectacular general, under normal circumstances he would have easily trounced his opponent with his superior forces, but now he was pitted against the tactically brilliant Sertorius. Plutarch describes the unequal campaign which followed: After an unsuccessful push towards the
Tagus in 79 BC, and suffering a defeat by Sertorius at
Lacobriga in 78 BC, Pius was forced to ask for help from Lucius Manlius, the governor of
Gallia Transalpina, but Manlius was defeated by Sertorius's legate
Lucius Hirtuleius upon entering the Iberian peninsula and had to retreat. The end result was that an exhausted Metellus was pushed out of his province (Hispania Ulterior). Metellus probably had a security problem. Sertorius was rumored to have many spies in his camp. On a later occasion a young officer asked Metellus the intention behind one of his order. He retorted: "If the shirt on my back knew what I have in mind, I would take it off and throw it into the fire." When the consuls of 78 BC declined to join Metellus as proconsuls once their terms ended, the Senate in late 77 BC, hearing of Metellus' ongoing reverses at the hands of Sertorius, decided to send
Gnaeus Pompeius Magnus with a large army to give Metellus what assistance he could, while Pius' governorship was prorogued. Both men worked well together, but were hard pressed to win any encounter with Sertorius himself. With Pompey's arrival in 76 BC, Sertorius turned his attention to him, inflicting severe losses on the Pompeian army at the
Battle of Lauron. Unfortunately for Sertorius, his legates were not able to contain Metellus, and he arrived just in time to save Pompey. Against Sertorius's legates Metellus and Pompey had more success. In 75 BC, Pompey defeated Sertorius's legates
Marcus Perperna and Gaius Herennius at the
Battle of Valentia while Metellus defeated Hirtuleius at the
Battle of Italica.
Italica The battle was Metellus' first major victory in the Sertorian War. It freed Metellus' army from the western theatre and allowed him to march against Sertorius' rear in the eastern theatre. Metellus and Hirtuleius were campaigning near the Roman colony of
Italica when Hirtuleius made the mistake of trying to force his opponent into a pitched battle. He mustered his army soon after dawn and marched on Metellus' encampment. Metellus mustered his troops too, but kept them behind his entrenchments until noon. It was extremely hot and Hirtuleius' troops were soon sweltering while Metellus' legionaries remained relatively fresh. 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. He had observed that Hirtuleius had posted his strongest units in the centre of his battle-line. When the battle finally commenced Metellus held back his own centre and concentrated on winning on the flanks. After defeating his opponent's flanks he enveloped Hirtuleius' centre and slaughtered them. This was the classic tactic used by
Hannibal at
Cannae almost a century and a half previous. Hirtuleius lost 20,000 men at Italica and fled north to join his commander Sertorius who was squaring off against Pompey.
Sucro and Saguntum Metellus came to the aid of Pompey after his near defeat at
Sucro. They then followed Sertorius inland to a town called Segontia and finally won a
battle against Sertorius himself. Metellus was acclaimed
imperator by his men. Plutarch remarks that this battle was forced upon Sertorius. This was probably done by his Celt-Iberian troops who wanted to defend Segontia, one of their native towns. The fighting started at noon and lasted well into the night. Sertorius first fought Pompey while his legates Perpenna and Hirtuleius fought Metellus. After Hirtuleius had fallen Sertorius switched places with Perpenna and launched several personally-led attacks on Metellus. (Sertorius probably reckoned Metellus' army would break without its leader.) Metellus stood his ground and in the course of the fight he was wounded by a spear. This turned out to be a turning point in the battle, for Metellus' men counter-attacked in revenge and pushed back the Iberians.
The final years Metellus Pius spent the winter of 75–74 BC in Gaul, where he received two legions in reinforcements. Upon his return to Hispania in 74 BC, he captured the towns of
Bilbilis and
Segobriga, before joining Pompey at the siege of
Calagurris. They were forced to raise the siege when Sertorius approached, after which Pius returned to Gaul. He then offered a reward of 100 silver talents and 20,000 acres of land to any Roman who would betray Sertorius. This resulted in Sertorius no longer trusting his Roman bodyguard and exchanged it for an Iberian one. Pius' governorship ended in 71 BC with the end of the war. He disbanded his army after crossing the
Alps, and celebrated a
triumph together with Pompey on December 30, 71 BC. Regardless of the triumph, during those eight years of resistance he was unable to conclusively defeat Sertorius, and it was only after Sertorius' assassination by his own men that the rebels were forced to cede to the military ability of Metellus Pius. ==Later career==