[1][2] A member of the celebrated plebeian gens Junia, Silanus first appears in history in 216 BC, when he was appointed prefect over the Roman garrison at Neapolis, one of the cities of Magna Graecia that had requested protection from the Carthaginian general Hannibal.
[5][6] In 210 BC, Silanus' imperium was prorogued for a second time,[i] and he accompanied the proconsul Scipio Africanus to Hispania, where he remained for the duration of the Iberian campaign.
[8][9][7] When Scipio took his army to conquer Carthago Nova in 209, Silanus remained in command of the forces south of the Iberus, holding the region the following year.
[10][11][12] In 207, at Scipio's direction, he attacked a large army that had been gathered by the Carthaginian commanders Hanno and Mago in Celtiberia, utterly defeating them with his much smaller force.
When Scipio traveled to Numidia to meet with Syphax, he left Silanus in charge of the Roman forces based at Carthago Nova, while Lucius Marcius Septimus was placed in command at Tarraco.