[4] As a result of his fidelity, he was given the agnomen "Pius" for the constancy and inflexibility with which he fought for his father's political rehabilitation and return to Rome.
[5] The outbreak of the Social War saw him employed as a legate in late 89 BC, probably serving the consul Pompeius Strabo in the northern theatre; he won some battles against the Marsi.
[7] During his praetorship, he was tasked with enrolling the Italian allies as new Roman citizens within sixty days, in accordance with the lex Plautia Papiria.
In 87 BC, Metellus Pius' command was extended, with his appointment as propraetor, responsible for continuing the war against Samnium.
During the early phase of this conflict, the Senate, fearing that they may need additional troops and commanders, ordered Metellus Pius to negotiate a peace with the Samnites.
[13] Arriving in Africa by early 86 BC, Metellus Pius started raising an army from his clients, with the intent of joining Lucius Cornelius Sulla, the principal opponent of Cinna and Marius.
[19] Upon his arrival, he drove out Metellus who fled to Numidia; pursued here, he and the Numidian king Hiempsal II were forced to flee onwards to Mauretania.
[22] Regardless, recognizing Metellus as possessing propraetorian imperium and his influence as a member of the powerful Metellan faction, Sulla made him his principal subordinate.
[23] By July 83 BC, the Senate, under the direction of the consul Gnaeus Papirius Carbo, declared Metellus a public enemy.
[25] When word of Sulla's victory at the Battle of Sacriportus reached them, Carbo retreated to his base at Ariminium, severely harassed by Pompey who acted as Metellus's cavalry commander.
[25] Metellus then achieved a victory over the consul Carbo and his general Gaius Norbanus at Faventia, pacifying Cisalpine Gaul for Sulla.
[29][30] Metellus Pius used his position to reward Quintus Calidius, who had helped bring his father back, by supporting his bid for the praetorship.
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.
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.
The light armour and consequent agility of his Iberian warriors meant Sertorius was constantly shifting his 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 somewhat inclined to ease and luxury, while Sertorius was full of mature vigour. ...
[38]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.
[43] 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.
[47] 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.
After Hirtuleius had fallen Sertorius switched places with Perpenna and launched several personally-led attacks on Metellus.
Sertorius in the meantime had regrouped his men and in the evening launched an unexpected attack on Metellus' camp, and attempted to exploit its vulnerable position by cutting it off with a trench.
Upon his return to Hispania in 74 BC, he captured the towns of Bilbilis and Segobriga, before joining Pompey at the siege of Calagurris.
When the former plebeian tribune and associate of Pompey, Gaius Cornelius, was accused of maiestas, the prosecution called on as witnesses a number of key anti-Pompeian former consuls, including Metellus Pius.
Therefore by his will he adopted a member of the patrician family Cornelia, son of Publius Cornelius Scipio Nasica, and maternal grandson of Lucius Licinius Crassus, great-grandson of Quintus Mucius Scaevola Augur and great-great-grandson of Gaius Laelius Sapiens.
He received name Quintus Caecilius Metellus Pius Scipio Nasica and further became the consul of 52 BC and father-in-law of Gnaeus Pompey the Great.
Metellus Pius is a prominent character in the novels The First Man in Rome, The Grass Crown and Fortune's Favorites by Colleen McCullough.
He is also mentioned in John Maddox Roberts' SPQR series as the fictional main character Decius Caecilius Metellus' uncle.