- Carthage had a much better naval force at the beginning of the Punic wars. In fact, Rome didn't have a navy at all. The only reason they won this was because a storm sank a Carthaginian vessel, which the Romans copied.
- Elephants. Yes, you're reading this right. At around 218 BC, 2 legions were sent to defeat Hannibal's army of 60k soldiers. The Roman legions were crushed to death by the war elephants.
- Hannibal himself. He was a very strategic person, using things like the "Pincer Maneuver". This method killed 70k legionaries and is still studied in modern military today.