All of Hispania south of the Ebro river is under Carthaginian control in 210 BCE, the year of Scipio's arrival.

Hannibal's brothers Hasdrubal and Mago, and Hasdrubal Gisco, are the generals of the Carthaginian forces in Hispania, and Rome is aided by the inability of these three figures to act in concert.

The Carthaginians are also preoccupied with revolts in Africa.

The Carthaginian armies disperse in the interior of Iberia in 209 BCE, possibly to maintain control over the Iberian tribes, on which they are dependent on for soldiers and provisions.

Scipio, landing at the mouth of the Ebro, is able to surprise and capture Carthago Nova (New Carthage), the headquarters of the Carthaginian power in Hispania, which had quickly grown as a trading and military post.

He obtains a rich cache of war stores and supplies, and an excellent harbor and base of operations.

Scipio's humanitarian conduct toward prisoners and hostages in Hispania helps in portraying the Romans as liberators as opposed to conquerors.

Livy tells the story of the capture of a beautiful woman by his troops, who offered her to Scipio as a prize of war.

Scipio was astonished by her beauty, but discovered that the woman was betrothed to a Celtiberian chieftain named Allucius.

He returned her to her fiancé, along with the money that had been offered by her parents to ransom her.

While Scipio was long known for his great chivalry, Scipio doubtless also realized that the Senate's first priority was the war in Italy, and in the midst of the Carthaginian base in Hispania, he was to be outnumbered without much hope of reinforcement.

It was paramount therefore that Scipio cooperate with local chieftains to both supply and reinforce his small army.

The woman's fiancé, who soon married her, naturally brought over his tribe to support the Roman armies.

Scipio fights his first set piece battle later in 209 BCE, driving back Hasdrubal Barca from his position at Baecula on the upper Guadalquivir.

Fearing that the armies of Mago and Gisco will enter the field and surround his small army, Scipio's objective is, therefore, to quickly eliminate one of the armies to give him the luxury of dealing with the other two piecemeal.

The battle is decided by a determined Roman infantry charge up the center of the Carthaginian position.

Roman losses are uncertain but may have been considerable in light of an effort by the infantry to scale an elevation defended by Carthaginian light infantry.

Scipio then orchestrates a frontal attack by the rest of his infantry to draw out the remainder of the Carthaginian forces.

Hasdrubal has not noticed Scipio's hidden reserves of cavalry moving behind enemy lines, and a Roman cavalry charge creates a double envelopment on either flank led by cavalry commander Gaius Laelius and Scipio himself.

This breaks the back of Hasdrubal's army and routs his forces—an impressive feat for the young Roman versus the veteran Carthaginian general.

Despite the Roman victory, Hasdrubal manages to retreat with two thirds of his army intact.

Much historical criticism has been leveled Scipio’s inability to effectively pursue Hasdrubal, who will eventually cross the Alps only to be defeated by Gaius Claudius Nero at the Battle of the Metaurus.

Hasdrubal Gisco, after suffering defeat at Ilipa in 206 BCE, had returned to Africa and Mago had retreated to Gades (modern Cádiz) with the remnants of his army.

His deputy, another Hanno, is defeated by L. Marcius, and Mago is unable to take advantage of the rebellion of Hispanic tribes under Indibilis or the mutiny of the Roman troops in 205 BCE.

He leads a raid on Carthago Novo, believing the city to be lightly held, and suffers severe losses.

Upon returning, he finds the gates of Gades barred, and sails away to the Balearic Islands after crucifying the city magistrates for treason.

The Port of Mahón in the Balearic Islands, allegedly founded by Mago, still bears his name today. (The local egg sauce that is now consumed all over the world is called mayonnaise, named after the city.)

From Mahón, Mago leads a campaign to invade Italy (this time by sea) with fifteen thousand men in early summer of 205 BCE.

The army sails from Minorca to …

…Liguria under the escort of thirty Carthaginian quinqueremes.

Mago manages to capture Genoa and …

…Savona.

Scipio sails at the commissioners' bidding from Sicily in 204 BCE at the head of his army of volunteers and lands near Utica.

Carthage, meanwhile, has secured the friendship of Syphax, whose advance compels Scipio to abandon the siege of Utica and dig in on the shore between there and Carthage.

The arrival of four thousand Celtiberian mercenaries from Southern Iberia makes the Carthaginians determined to make one more effort to stop the armies of Scipio from advancing across North Africa.

New levies are raised in Carthage and in Numidia, and soon Hasdrubal and Syphax find themselves at the head of an army of thirty thousand men.

Scipio feigns negotiations, then mounts a treacherous surprise attack on Syphax, approaching by stealth and setting fire to the enemy camp, where the combined armies of the Carthaginians and Numidians become panicked and flee, and are mostly killed by Scipio's army.

Though not a "battle," both Polybius and Livy estimate that the death toll in this single attack exceeded forty thousand Carthaginian and Numidian dead, and more captured.

Hasdrubal Gisco and Syphax, both men having succeeded in escaping from their camps, which Scipio and his Numidian ally Masinissa had destroyed with the aid of and Laelius, fall back with a few followers who had also escaped the massacre.

Scipio, his command extended until the end of the war, marches to meet Hasdrubal and Syphax at a place called the Great Plains.

The charge of the Roman cavalry causes the Carthaginian infantry and cavalry flee from the field; only the Spanish infantry remain standing, defending themselves fiercely.

The number of Spanish mercenaries is about equal to the first line of the Romans, the hastati.

Then Scipio orders his principes and triarii to march from behind the hastati and attack the flanks of the Spanish mercenaries, who are routed, with only a handful managing to escape.