After the Roman defeats at Castulo and Ilorca, the situation in Spain was desperate. The Senate appointed C. Claudius Nero to command there, but his presence was to prove only a temporary affair. In 210 BC the desperation was apparent in the granting of imperium to the young Publius Cornelius Scipio. At only 25 years of age, the legal age for a praetorship, Scipio, likely in sympathy over the death of his father and uncle, was unanimously elected the overall command of the campaign in Spain. He left Rome with an army of 10,000 infantry and 1,000 cavalry and like his uncle before him, landed at Emporiae. Consolidating with the remaining forces still left in Spain, he began his campaign with 28,000 infantry and 3,000 cavalry, and would receive no reinforcements from Italy for the remainder of the war.
From his base in Tarraco, Scipio immediately set about boosting the morale of his troops and securing alliances with local Celtiberian tribes. Also scouting the enemy during the winter before his first campaign, he discovered that the Carthaginian forces were not only still divided in three forces, but that in-fighting between them seemed to show a lack of cooperation. Hasdrubal, Mago and Hasdrubal Gisgo each had as many troops as Scipio's single army, but it became apparent that 3 separate campaigns of conquest could be planned. The Carthaginian base of Carthago Nova soon developed as Scipio's first target, with a garrison of 1,000 men he surmised that its defeat would not only be easy, but would be a major blow to the enemy in the heart of its territory.
In early 209 BC, Scipio set out with 25,000 men and 30 ships under the command of Gaius Laelius. Arriving at Carthago Nova in complete surprise, he fortified his own position to protect himself from Carthaginian reinforcements and prepared for the assault on the city. After two attempts to take the city by direct attack, Scipio employed a strategy of assaulting the small garrison from several sides. Completely outnumbered and unable to face the Romans from so many points, a marine force was able to storm the gates and gain entry to the city. At first, the Romans massacred the inhabitants in order to flush out any remaining resistance but when the Carthaginian commander (another Mago) surrendered, Scipio ordered the end of the slaughter.
The capture of Carthago Nova not only drove a wedge into the heart of Carthaginian Spain, it gave the Romans much needed military stores and supplies, access to local silver mines, an excellent harbor and a perfectly positioned base for further operations in southern Spain. Scipio's treatment of the locals once the battle was over was exemplary. Carthaginian citizens were set free and they were allowed to keep their property. Artisans were promised freedom if they continued to work in Roman service. He also recruited heavily among the locals as naval rowers and additional auxiliary forces, not only supplementing his own forces, but giving the impression that the people were allies to Rome rather than enemies.
After Carthago Nova was secure, Scipio moved his main force to Tarraco where he spent the remainder of the year training and drilling his men. Under Scipio, the Romans abandoned their traditional Italian gladius for one used by Celtiberians. The Spanish short sword (Gladius Hispaniensis) was better suited for close quartered legionary tactics and it would soon become the primary sword of the entire Roman army.
The Carthaginians meanwhile, seriously devoid of any naval capacity were unable to retaliate at Carthago Nova. In the aftermath of its loss to Rome, they had little choice but to keep focused on quelling local tribes before they defected to the enemy. In effect, Rome had accomplished in Hispania what Hannibal had attempted to do in Italy, turning the inhabitants against the traditional power. Hasdrubal had begun recruiting an army to reinforce Hannibal in Italy, but Scipio and his extensive network of scouts were well aware of these plans. In the campaign year of 208 BC, Scipio marched south to Baecula to meet the unsuspecting Hasdrubal.
Near the Baetis River, the battle of Baecula faced 40,000 to 50,000 Romans against as many as 30,000 Carthaginian forces. Hasdrubal immediately withdrew to his camp and prepared for the defense when the Romans approached. While the enemy formed in a defensive posture, Scipio was able to outflank the enemy and quickly took command of the field. Hasdrubal wisely realized he was outmatched and retreated to safety in the Carthaginian dominated interior of Hispania. While the Carthaginians lost as much as half or 2/3rds of its army, Hasdrubal was able to save enough of it to continue with his planned reinforcement of Hannibal. Scipio, though later widely criticized, knew that pursuit into the interior of Spain would have been folly and let Hasdrubal go, choosing instead to focus on the remaining Carthaginian forces and strongholds.
After Baecula, Hasdrubal moved to reinforce Hannibal in Italy with his remaining army and Scipio moved against the armies of Mago and Hasdrubal Gisgo. Reinforced by the local Spanish tribes who hailed him as a King (though he refused this), Scipio was in excellent position to deal a deathblow to Carthage. One of his generals, Silanus, was sent with 10,000 infantry and 500 cavalry on a forced march to attack Mago in his training camp. Recently reinforced by Hanno from Africa, the Carthaginians outnumbered the Roman force, but Silanus' attack was a complete surprise. Mago and Hanno were utterly defeated and any recent Carthaginian levies were scattered beyond hope of recovery. Hanno was captured while Mago salvaged what little was left of his army and retreated to Gades joining Hasdrubal Gisgo, who had wisely moved out of reach of Scipio when news of the battle had reached him.
Meanwhile, an army under the command of Marcius harassed and assaulted pro-Carthaginian Iberian tribes in an attempt to eliminate what remained of their recruiting base. Both he and Scipio spent the remainder of the year spreading Roman control while preparing for the final campaign to eliminate the Carthaginian presence in Hispania. News of Hasdrubal's complete defeat in upper Italy after escaping Scipio arrived at this time and Carthage was clearly on the defensive in all theatres for this first time in the war. While the year 207 BC was drawing to a close, both sides prepared for what would prove to be the final battle between the two forces in Hispania.