Hannibal is most famous for what he did in the Second Punic War. He marched an army from Iberia over the Pyrenees mountains and the Alps mountains into northern Italy and defeated the Romans in a series of battles. At the Battle of Cannae, he defeated the largest army Rome had ever put together. The Roman army at Cannae is reckoned at 16 legions and a total of 86,000 men. Over 80% of this army was killed or captured, including many of its commanders.