Mago fought at the side of Hannibal in the invasion of Italy, and played a key role in many battles. At the Battle of the Trebia, he commanded the detachment that ambushed the Romans, breaking down their battle array. After the battle, Mago commanded the rearguard of the Carthaginian column as it marched south towards Latium through the marshes of Aino. In the Battle of Cannae, Mago and Hannibal took position with the Gallic infantry at the center, in the most vulnerable and crucial position of the formation.