Role at Pydna (168 BC)
The Third Macedonian War began in 171 after King Perseus of Macedon had allegedly tried to assassinate Rome's ally Eumenes II of Pergamon (among many other reasons). However, Perseus managed to defend his kingdom rather well for a couple of years. In 168 Rome mustered a strong army under the consul Lucius Aemilius Paullus to put an end to the conflict. Paullus chose Corculum to serve as one of his military tribunes, probably for family reasons, as Paullus was also the brother-in-law of Scipio Africanus, and the Aemilii were long allies of the Cornelii. Despite their family connections, ancient historians' accounts show that they had difficult relations throughout the campaign.
Most of what is known on the final military operations of the Third Macedonian War derive from two lost—and conflicting—sources, quoted by later classical writers. The first one is the Histories of Polybius, who talked to several witnesses of the war (Romans and Macedonians); his story was mostly followed by Livy. The second account is a letter or memoir written by Corculum himself and addressed to a king, possibly Massinissa of Numidia, as the Cornelii had personal ties with him since Scipio Africanus. This memoir was used by Plutarch in his Life of Aemilius, who notes the discrepancies with Polybius. The memoir is considered to be one of the earliest Roman autobiographical texts, second to a long letter of Scipio Africanus to Philip V, which likely inspired Corculum. Opinions on the memoir have widely diverged among modern historians; some consider it to be a faithful account of the events, while others have rejected it as an act of self-advertising, with further opinions in-between.
In southern Macedonia Perseus had fortified the north bank of the Elpeus River to prevent Paullus from entering his kingdom from the south. Paullus therefore designed a circling movement around Mount Olympus to flank Perseus. He appointed Corculum to head this operation, assisted by Quintus Fabius Maximus Aemilianus (Paullus' natural son, adopted into the Fabii); Corculum said he and Fabius volunteered. According to Polybius, Corculum took 5,000 men with him (Corculum said 8,320 men in his memoir). At first, he faked a movement to the sea, but once at Heracleum he told his staff the real purpose of the mission, and moved by night to Pythium (departing in the night of 17 and 18 June 168). Meanwhile, Paullus attacked the Macedonians to prevent them from detecting Corculum's move. Pythium was successfully taken in the early morning of 20 June 168, perhaps because the garrison was still asleep. Corculum's version is different, as he wrote that a deserter warned Perseus of the flanking manoeuvre; he therefore had to face a force of 12,000 men, whom he defeated—and also personally killed a giant Thracian. Livy, following Polybius, tells the Macedonians were only 5,000, a number favoured by modern historians. In any case, after hearing of the capture of Pythium, Perseus retreated north, and set his camp just before Pydna. Corculum then completed the turning movement around Mount Olympus and met with Paullus (who had followed Perseus) on 21 June. Livy says that Corculum and other officers in Paullus' staff wanted to attack Perseus immediately, but the consul preferred to delay in order to rest the troops.
The Battle of Pydna started on 22 June, after an unexpected skirmish between foraging soldiers. The phalanx advanced against the legions, but the uneven field broke its ranks, so Roman soldiers could pass through the gaps thus created and defeat smaller bits of phalanx individually, resulting in a crushing victory for the Romans, who only lost 80 men (according to Corculum). Corculum said he led the Roman right wing, which had to fight Perseus' Thracian contingent, but it might be another rewriting of the events from him. Paullus then sent him to Amphipolis in order to ravage the area and prevent Perseus from counter-attacking, since he had been seen heading to this city after his defeat. Once there, Corculum likely informed Paullus that Perseus had fled to Samothrace, where he was finally captured by Gnaeus Octavius, who commanded the fleet. According to Plutarch, Perseus initially wanted to surrender to Corculum because he trusted him more. It illustrates the very high status enjoyed by the Scipiones among Mediterranean courts, almost that of a royal family.
It seems that Corculum prevented Amphipolis from being punished by Paullus for having opened its gates to Perseus in his flight, because a statue of him was later erected in the city's gymnasium. Corculum's moderation against the defeated Macedonians and Greeks mimicked that of Africanus after his victories against Carthage and the Seleucids, and contrasted with the brutality of Aemilius Paullus, who enslaved 150.000 people in Epirus on his way back to Rome. It was "the greatest slave-hunting operation in the history of Rome". Plutarch's criticism of Paullus on this point might derive from an hostile comment by Corculum in his memoir, who could have disapproved Paullus' enslavement of the Epirotes.
Corculum remained tribune of the soldiers in 167, and was sent by Paullus to raid Illyria in retaliation for having supported Perseus.