There is Little doubt that Hannibal of Carthage (247-183BC) was a great general and tactician, showing his skills in particular during the Second Punic War. However, It also must be noted that there was never any real chance of Carthage winning against Rome despite the outcome of early battles or the brilliance of it"s general.
Hannibal was the son of the great Carthaginian general Hamilcar Barca. According to Polybius and Livy, the main Latin sources for his life, Hannibal was taken to Spain by his father and at an early age was made to swear an oath of eternal hostility to Rome. From the death of his father in 229BC until his own death, Hannibal devoted his life to the constant struggle against the strengthening Roman republic. His Background was military, with his first commands given to him by his father's son-in-law Hasdrubal, who was the Carthaginian general in Spain following Hamilcar's death. In 221 the general was assassinated, and Hannibal had experienced such success in his role as an officer that the army quickly proclaimed him it's commander in chief at the age of 26. The Carthaginian government was quick to ratify this appointment.
Hannibal's first actions were aimed at consolidating Punic control of the Spanish areas. He began to fight and conquer various Spanish tribes who weren't yet under Carthage's wing. In 219BC he laid siege upon the independent Iberian city of Saguntum, south of the Ebro river. In the treaty made between Rome and Carthage following the first Punic war(264-241), The Ebro river had been set as being the furthest north that the Carthaginian influence would be allowed to exist. Yet while Saguntum did comply with this requirement, the Romans had a friendship with this city and saw the Punic attack on it as an act of war. Rome gave Carthage and ultimatum - either give up Hannibal, or go to war. The Carthaginian council chose to support their general and accepted the declaration.