One of their sisters was married to another Hasdrubal (surnamed "the Fair"), the leader of the popular party in Carthage, and Hamilcar's successor after his death in 229. This Hasdrubal consolidated Carthaginian power with diplomatic means, and concluded a treaty with Rome in which he accepted the river Ebro as northern frontier. In 221, he was assassinated by a Celtic mercenary, and succeeded by Hannibal.
The new commander returned to his father's more aggressive politics. In 220 he captured Salamanca and in 219, he started to besiege Saguntum, a Roman ally, but situated south of the Ebro. Since Rome was occupied with the Second Illyrian War and consequently unable to support the town, Saguntum fell after a blockade of eight months. The Romans felt offended by what they considered to be a violation of the treaty, and demanded that the Carthaginian government would hand over the man who they thought was responsible.
While these negotiations were still going on, Hannibal continued to extent Carthage's territory: he appointed his brother Hasdrubal as commander in Iberia, and in May 218 he crossed the river Ebro: a direct provocation of Rome and the outbreak of the Second Punic War, which was to last until 202. Hannibal continued across the Pyrenees and Rhône, crossed the Alps, and invaded Italy, where he defeated the Romans in several battles, culminating in a brilliant victory at Cannae (2 August 216). After this, the Romans evaded direct engagement with the Carthaginian leader.But in the meantime, the Romans had opened a second front in Iberia. They had sent proconsul Gnaeus Cornelius Scipio Calvus to the country north of the Ebro, where he had gained a first foothold at Emporiae. The Carthaginian commander responsible for this area, Hanno, was defeated, and the Romans advanced to the south, to Tarraco (Tarragona). Hasdrubal arrived too late to defend the city, was repulsed, and went back to New Carthage, the Carthaginian capital in Iberia.
This was a considerable Roman success, because the conquest of Catalonia meant that Hasdrubal could no longer reinforce his brother in Italy. In 217, the Carthaginian supreme commander in Iberia tried to turn the tables. With a large army and a fleet, he proceeded to the north. Scipio was outnumbered, but received ships from Massilia, and overcame Hasdrubal in a naval engagement off the mouth of the Ebro. Not much later, he received reinforcements, commanded by his brother, proconsul Publius Cornelius Scipio. Immediately, the two men crossed the Ebro, where they impressed the Spanish tribes and garrisoned two ports.
Next year, the war came to a standstill. The Scipios were consolidating their positions, and Hasdrubal was active in Andalusia, where the Turdetani were restless. Perhaps, both sides were also looking to the east, where Hannibal was victorious at Cannae.
In 215, Hasdrubal, who must have been optimistic after his brother's greatest success, again attacked. With a reinforced army, he advanced along the coast, and offered battle at Ilerda, close to the mouth of the Ebro. Again, he was routed: the first Roman victory in an open battle during the Second Punic War. Immediately, the Carthaginians sent reinforcements, commanded by Hannibal's brother Mago Barca. This army had originally been intended for use in Italy.
Unfortunately, the troops could not be used in Iberia either. In West-Numidia, king Syphax, who had never loved the Carthaginians, was becoming dangerous, and Hasdrubal had to cross the Mediterranean to restore order (214). He was not without success, but in 213, Syphax was able to conclude an alliance with the Romans, and could make a beginning with restoring his power.
In Italy, Hannibal had conquered the deep south (Tarentum in 213), and the Romans were deploying their troops far away from Rome, besieging Capua and Syracuse. In 211, Hannibal marched on Rome, perhaps hoping to take the city, but certainly hoping to force his opponents to raise the siege of Capua and admit that they had lost southern Italy forever. At the same time, Hasdrubal was to expel the Scipios, who had by now proceeded to Saguntum. Hasdrubal's brother Mago commanded a second army, and a nobleman named Hasdrubal, son of Gesco, commanded a third force.
It seems that the Scipios did not know about the size of the Carthaginian forces, because they marched separately. In 211, they were defeated by Hasdrubal and his allies, and killed. However, Hasdrubal was unable to exploit his victory. The Romans found new leaders in Lucius Marcius Septimus and Gaius Claudius Nero, and Mago and the other Hasdrubal wanted to use the success for themselves. Because in the meantime, Capua and Syracuse had fallen, the Romans could send reinforcements. The Carthaginians had simply failed to seize their opportunity.
Late in 210, the tide was definitely rolling back. The son of Publius Cornelius Scipio, who had the same name, arrived in Tarraco, ready to seize the initiative again. When he understood that the three Carthaginian commanders were still on bad terms and far from each other, he unexpectedly stroke at New Carthage. Early in 209, he laid siege to the city, while his friend Laelius blocked the harbor with the Roman navy. The Carthaginian capital was taken almost immediately, and Hasdrubal, who was campaigning in Central Iberia, arrived too late.
Because many Spanish tribes understood from where the wind was blowing, they switched sides, and the three Carthaginian armies were now reduced to Andalusia. Here, Hasdrubal occupied Castulo, in the valley of the Upper Guadalquivir, which was the only place where Scipio could invade Andalusia. Early in 208, the two armies met, and the Romans defeated the Carthaginians. The road to Andalusia was now open. In 207, Mago was forced to join Hasdrubal, son of Gesco, who was defeated in 206 at Ilipa. This was the end of the war in Iberia, which became a Roman province.
Meanwhile, Hasdrubal had regrouped his army. Instead of retreating to Cordoba or Sevilla, he unexpectedly marched to the north, through Central Iberia, through the valley of the Upper Ebro, and across the Pyrenees, Rhône, and Alps. In May 207, he and his 20,000 men arrived in northern Italy, just as Hannibal had done in 218. It was a bold move, and if he could join his brother, the situation in Italy, which had slowly deteriorated for the Carthaginians, would suddenly improve.
The Romans had elected Gaius Claudius Nero, the man who had defended the Ebro after the death of the two Scipios, as consul, and gave him Marcus Livius Salinator as his colleague. The former had to guard Hannibal, the latter was supposed to defeat Hasdrubal, who had recruited additional soldiers. His army now counted 30,000 men, but the Romans were not impressed. Claudius left four legions to watch Hannibal, and marched 360 kilometers in six days to join his colleague at the river Metaurus. Hasdrubal now faced superior numbers, and was defeated. He was last seen leading a charge, and died fighting.
One of the officers of his army, Hamilcar, continued the struggle until 197.