Final answer:
The Romans countered the Carthaginian threat by adapting their military tactics and leveraging their resilience, rather than hiring external forces. They shifted to effective naval warfare and guerrilla tactics, leading to significant victories including the crucial Battle of Zama which ended the Second Punic War in Rome's favor.
Step-by-step explanation:
The Romans did not hire an external force to specifically stop the Carthaginians from attacking or winning. Rather, they built upon their resourcefulness and military strength to counteract the Carthaginian threats during the Punic Wars. After several defeats and learning from their engagements, the Romans developed effective naval warfare strategies and managed to strand the Carthaginian army in Sicily. In 241 BCE, Carthage sued for peace and the first Punic War concluded with Rome seizing control of Sicily.
However, the Carthaginians, under the leadership of General Hannibal, sought revenge, notably in the Second Punic War, where they achieved several victories against Rome. This time, the Romans adapted their tactics, engaging in a form of guerrilla warfare against Hannibal's forces in Italy. Despite Hannibal's innovative tactics and his initial success, the Romans continued to apply pressure and managed to cut off reinforcements for Hannibal's army from Spain and Africa. The deadlock lasted until the Roman General Publius Cornelius Scipio launched an offensive that forced Hannibal to defend Carthage in North Africa. At the Battle of Zama in 202 BCE, Rome defeated Hannibal, culminating in a peace treaty that stripped Carthage of its territories.