How did Rome gradually defeat the carthginians?

Answer 1

There were three Punic Wars between the Romans and the Carthaginians. I guess you are referring to the Second Punic War where Hannibal invaded Italy. The factors that contribute to Rome's victory were:

1) Hannibal lost his siege machines when he crossed the Alps in the snowy winter to enter into Italy from the Carthaginian possessions in Spain. Without these he could not attack Rome. Thus, after routing the Romans twice (in northern and central Italy), he went to southern Italy instead of heading for Rome.

2) The Romans adopted a strategy of attrition: they avoided open battle and harassed him with guerrilla tactics to wear him down.

3) Hannibal smallish invasion army needed Rome's allies in Italy to switch sides to increase his forces and weaken Rome. When this materialised in the south, after winning the battle of Cannae (in the south), it proved insufficient. Hannibal set up his headquarters in Capua (Italy's second largest city near Naples) which had switched sides. However, he failed to seize or retain two strategic cities in this area and two attempts at sending him reinforcements were foiled. The Romans besieged Capua. Hannibal had to leave the area. Moreover, Rome's allies in central Italy remained loyal.

4) The military manpower of Rome and her allies was massive. Rome was able to keep raising new armies and gradually regained control of southern Italy. They also suppressed a rebellion in Sicily. Hannibal lost many men and half of his cavalry. A cavalry far superior in numbers had been a key to his victories. His tactics became more defensive.

5) The Romans intercepted and routed the army of Hasdrubal, Hannibal's brother. He was bringing and siege machines and the badly needed reinforcements from Spain to Hannibal. At this point Hannibal's campaign in Italy came to a dead end. He spent the last four years of his campaign in italy stuck in Calabria (the toe of Italy) whose mountains were easy to defend.

6) In Carthage the peace faction refused to send reinforcements to Hannibal from Africa.

7) The Romans found in Scipio Africanus a general who could match Hannibal. He defeated the Carthaginians in Spain and Rome took over their Spanish territories. Reinforcements to Hannibal could no longer be sent from there. Carthage also lost her main source of wealth, the silver mines in Spain.

8) Scipio Africanus began a campaign in Tunisia (where Carthage was). Hannibal was recalled from Italy to fight in Tunisia. Scipio defeated him in the last battle of the war, the battle of Zama.

9) The western Numidians of Algeria switched alliance from Carthage to Rome. They had supplied half of Hannibal's cavalry. Now they supplied 2/3 of the Roman cavalry in the Battle of Zama, and played a key role in that victory.