News of the disaster caused a fresh outbreak of panic in Carthage, some calling for the return of Hannibal and his army, whilst others even suggested seeking peace with Rome. However, at this stage the majority of the Punic senate summoned by the suffetes were still in favour of continuing the struggle, so they ordered messages to be sent to Syphax, urging him to rejoin Hasdrubal. The king was at the city of Abba, where he had begun reforming his army. He remained loyal to Carthage, urged on by his wife, but also encouraged by the arrival with Hasdrubal of a contingent of recently raised Celtiberian warriors. There were in fact 4,000 of these tribesmen, but rumours encouraged by the Carthaginians inflated the number to 10,000 and spoke in extravagant terms of their ferocity and prowess. The Carthaginians' continued ability to raise mercenaries in Spain, despite their expulsion from the country gives an interesting indication of the minimal control the Romans exercised over the greater part of the Spanish Peninsula. Syphax went to join Hasdrubal after thirty days and their combined forces, something like 30,000 men, encamped in a strong position on the area known as the Great Plains, probably the modern Souk el Kremis.14
As soon as Scipio received reports of this new concentration of forces, he decided to march and confront them. Leaving his fleet and part of the army to continue the siege of Utica, he led out the remainder, reaching the edge of the Great Plains on the fifth day. It is uncertain how large the Roman force was, but likely that it was smaller than the enemy army. The Romans left behind their heavier baggage, clearly planning on a swift campaign. Scipio camped just under 4 miles from the enemy position and rested his army. On the next day, the Romans marched out into the plain and deployed into battle order a little less than a mile away from the Punic army. There was the usual skirmishing between the cavalry and light infantry, but neither side chose to force a general action on that day or the next two. On the fourth day, the rival commanders seem to have mutually decided to fight a battle and advanced their lines so far forward that a clash became inevitable. Hasdrubal formed his centre from his most reliable troops, the Celtiberians. Next to them on the right were the infantry salvaged from his old army, flanked by his cavalry, and on the left Syphax's Numidians. The Roman deployment was similar with the legions in the centre, presumably flanked by the alae, the Roman and Italian cavalry on the right flank and Masinissa's Numidians on the left.
The battle was decided very quickly as Masinissa's Numidians and the Italian horse swept away their counterparts in the first charge. Most of the Punic and Numidian infantry seems also to have collapsed into rout, probably pushed by the alae if these were in fact present, leaving the Celtiberians isolated. The fleeing troops all preserved the memory of recent defeat when these same Romans had stormed their camps, and their morale had evidently not yet recovered. Abandoned, the Celtiberian warriors continued to fight hard against the Roman legions, Livy claiming that their unfamiliarity with Africa deterred them from joining the flight. In numbers they at the very least roughly equalled the hastati of the two legions who probably formed the centre of Scipio's line. The Romans had deployed in the usual triplex acies, but rather than feed the rear lines into the combat, the legions performed another of the manoeuvres which were becoming the trademark of Scipio's armies. The principes and triarii turned into column and marched out from behind the hastati, wheeling to attack the Celtiberians in both flanks. It is unclear whether one entire line went to the right and the other to the left, or the separate legions divided so that half of the principes and triarii moved against each flank. Enveloped, the Spanish warriors were destroyed as an effective unit, very few escaping, but their sacrifice allowed much of the rest of the army to get away.15
After this victory Scipio summoned his consilium to discuss their next move. Roman magistrates serving in any capacity were expected to seek the advice of experienced men, but, whilst considering other viewpoints, a general was expected to make the actual decisions himself. The gathering of senior officers was then a convenient way of explaining a plan to the subordinates who would carry it out. Scipio decided to divide his army, keeping the main force himself to ravage the surrounding area, whilst Laelius took the remainder and went with Masinissa to restore the prince to power within his own tribe. Once again Scipio's men gathered rich plunder from the wealthy plains and began to find that some of the Libyan communities, weary of the heavy taxes imposed on them to support the Punic war effort, were willing to surrender to Rome. Encouraged, the general decided to make a demonstration against Carthage itself.16
Despite the dismay caused by another defeat, the Carthaginian Senate remained resolute, giving orders to prepare the city itself for a siege. In the last months considerable effort had been directed towards equipping and crewing a fleet, originally with the intention of threatening the Roman supply lines with Sicily. It was decided to send the fleet to Utica, which was now surrounded by a comparatively weak Roman force. At the very least this might raise the siege, but plans were also made to attack the Roman fleet which was, correctly, believed to be unprepared for naval combat. In addition, the momentous decision to recall Hannibal and his army was taken, a party of Punic senators being dispatched by sea to carry the message to the general.17
Scipio moved against Tunis, which was abandoned by its garrison. He was now about 15 miles from Carthage itself, able to see the city and its harbour. As the Romans watched they saw the Punic fleet putting to sea and immediately realized the threat to their own naval squadrons at Utica. Scipio gave the order to abandon the new camp and hastened back to castra Cornelia, the general perhaps riding on ahead, for he reached his base before the enemy ships. Realizing that there was no time to prepare the Roman squadrons for battle, since many had been adapted to carry siege engines, he had the ships lashed closely together, the transports three or four deep around a central line of galleys. On board were stationed 1,000 picked men, equipped with a great quantity of missiles. The Punic fleet had not hastened to reach Utica, and did not attack until the next day. This may simply have been a tactical error on the part of their commander, brought on by over-confidence, or perhaps reflected a desire to give the crews some sea training before they engaged. When they did attack, the Punic ships were able to make little headway against the solid barrier of Roman ships, especially since the transports were significantly higher than the low-slung galleys. However, the Carthaginians managed to cut sixty transports free and towed them in triumph back to Carthage.18
It took around fifteen days for Laelius and Masinissa to reach the kingdom of the Maesulii. Syphax had raised another army to face them, mostly from his own tribe. In a confused battle his more numerous cavalry initially gained an advantage, but as Laelius' legionaries came up to support Masinissa's horsemen the tide began to turn. The close formations of the Roman infantry gave stability to the line, and provided solid points behind which their own horsemen could rally and reform before charging again. Steadily the Roman line pushed forward until finally Syphax's army broke. The king himself attempted to rally his men by personal example, but when his horse fell beneath him he was captured and taken to Laelius. On Masinissa's suggestion, Laelius then moved on Syphax's capital Cirta, taking it by surprise and easily capturing it. Sophonisba surrendered herself with great dignity to Masinissa, begging him not to hand her over to the Romans. Without informing Laelius, Masinissa impulsively decided to take her as his own wife. The creation of such a link between their closest ally in Africa and the Carthaginian nobility was obviously most unwelcome to the Romans, who believed the Numidians to be a fickle race in their loyalties, but Laelius agreed to allow Scipio to decide what should be done. After mopping up the few garrisons still loyal to Syphax, the victorious leaders returned to join Scipio. The captured Syphax bemoaned his fate, blaming his misfortune on Hasdrubal's daughter who had led him against his inclinations to war with Rome. Subtiy, he claimed that he was glad that his enemy Masinissa would now fall under her spell and suffer the consequences. This added to the Roman commander's suspicion of the young Numidian's action, perhaps especially because of his own refusal of similar temptations at New Carthage. Scipio declared that both Syphax and Sophonisba were captives not of Masinissa but of Rome, and could not be disposed of without his permission. The emotional Numidian sent a gift of poison to his new bride who, the product of a culture which told many tales of aristocratic suicide, took it without hesitation. So ended one of the most romantic and tragic episodes of the war. The next day Scipio confirmed Masinissa as king of his tribe in a public ceremony, lavishing him with praise and honours.19