Rome had decided to embark one army for Spain, and another for Sicily and Africa. Their preparations were incomplete.
Hannibal, of Carthage, then moved the War to Italy. Marching without Rome's knowledge. Cutting off it's resource of strength.
Hannibal arrived, and Rome could not oppose. Surprising them in Northern Italy. Roman troops pressed on, but Carthaginians had the superiority.
The Romans cut off resources from Hannibal, and he was denied more soldiers. Paired with a strategy of counter attack, on Carthage. Hannibal retreated back, to defend his home land. Leaving the Romans in victory once more.