<P> There were three military theaters in this war: Italy, where Hannibal defeated the Roman legions repeatedly; Hispania, where Hasdrubal, a younger brother of Hannibal, defended the Carthaginian colonial cities with mixed success until eventually retreating into Italy; and Sicily, where the Romans held military supremacy . </P> <P> After assaulting Saguntum in Hispania (219 BC), Hannibal attacked Italy in 218 BC by leading the Iberians and three dozen elephants through the Alps . Although Hannibal surprised the Romans and thoroughly beat them on the battlefields of Italy, he lost his only siege engines and most of his elephants to the cold temperatures and icy mountain paths . In the end he could defeat the Romans in the field, but not in the strategically crucial city of Rome itself, thus leaving him unable to win the war . </P> <P> Hannibal defeated the Roman legions in several major engagements, including the Battle of the Trebia (December 218 BC), the Battle of Lake Trasimene (217 BC) and most famously the Battle of Cannae (216 BC), but his long - term strategy failed . Lacking siege engines and sufficient manpower to take the city of Rome itself, he had planned to turn the Italian allies against Rome and to starve the city out through a siege . However, with the exception of a few of the southern city - states, the majority of the Roman allies remained loyal and continued to fight alongside Rome, despite Hannibal's near - invincible army devastating the Italian countryside . Rome also exhibited an impressive ability to draft army after army of conscripts after each crushing defeat by Hannibal, allowing them to recover from the defeats at Cannae and elsewhere and to keep Hannibal cut off from aid . </P> <P> Hannibal never successfully received any significant reinforcements from Carthage . Despite his many pleas, Carthage only ever sent reinforcements successfully to Hispania . This lack of reinforcements prevented Hannibal from decisively ending the conflict by conquering Rome through force of arms . </P>

Describe how the punic wars helped increase roman power