3. Battle Of Metaurus (207BC)
Hannibal had crushed the Roman Republic at Cannae, but, after reaching the outskirts of Rome, it became clear that he didn't have the resources to capture the city. He lacked the siege tools required to take Rome, and, worse still, the Romans knew that and chose to remain inside the walls and avoid confrontation. Hasdrubal, Hannibal's brother, was coming to aid the cause, with a force large enough to begin a siege on Rome. Realising that the brothers intended to combine their forces and march on Rome, Claudius Nero and Marcus Livius met up at Sena, half a mile south of Hasdrubal's army. The cavalry and infantry clashed in the centre, but the left wing of the Roman infantry appeared in danger of collapsing, so Nero left the right flank with most of his troops and joined the threatened section of the line. The Carthaginian cavalry retreated, allowing Nero's infantry to focus on the opposing troops. Hasdrubal was beheaded, his body taken to Hannibal's camp, and, after Scipio led an attack on Carthage, Hannibal was forced to head home. The Second Punic War was soon over, and, after the Third Punic War, Carthage was burned to the ground. What if Hannibal and Hasdrubal had combined forces? It's likely they would have marched on Rome, and, if they had have taken it, it's almost certain we'd remember the Carthaginian Empire, rather than the Romans.