For fifteen years, the Second Punic War had been fought almost everywhere except Carthage itself. Hannibal had terrorized Italy, crossing the Alps and winning catastrophic victories at Trebia, Lake Trasimene, and Cannae. Meanwhile, Scipio -- then barely in his twenties -- had been rebuilding Roman fortunes in Iberia, driving the Carthaginians out of Spain over five grueling years. By 205 BC, he had convinced the Roman Senate to let him carry the war to North Africa. After training his army in Sicily for a year, he landed near Utica in 204 BC with four legions and laid siege to the port city. The Carthaginians and their Numidian allies under King Syphax established camps nearby, and months of standoff followed before Scipio's devastating night raid shattered both forces.

The Carthaginian general Hasdrubal Gisco and King Syphax were not finished. They managed to rally their scattered troops and recruit fresh forces, including 4,000 Celtiberian mercenaries recently arrived from Spain. The combined army reassembled on the Great Plains, an area of relatively flat terrain in the upper Medjerda River valley, far enough from the coast to force Scipio into a long march. Scipio accepted the challenge. Leaving part of his force to maintain the siege of Utica, he advanced rapidly with his remaining legions and Numidian cavalry under Masinissa, a rival Numidian prince who had allied with Rome.

For five days, the two armies faced each other. On the fifth day, both sides drew up for battle. Scipio placed his Roman infantry in the center in the traditional three-line formation: hastati in front, principes behind, and the veteran triarii in reserve. His Numidian cavalry held one wing and Italian cavalry the other. When the lines clashed, the Carthaginian and Numidian levies on the flanks broke almost immediately, unable to withstand the disciplined Roman advance. The Celtiberian mercenaries in the center fought far more stubbornly. These were professional soldiers with nowhere to retreat -- they were strangers in Africa, unfamiliar with the terrain, and could expect no mercy if captured. They held their ground until the Roman cavalry, having routed the flanks, swept in from both sides. Surrounded, the Celtiberians were annihilated.

The battle of the Great Plains broke Carthage's field army. Syphax fled westward to his kingdom in Numidia, where Masinissa and the Roman legate Laelius pursued and captured him. Hasdrubal Gisco retreated to Carthage, where the political situation was unraveling. The Carthaginian senate sued for peace, and Hannibal was recalled from Italy -- a move that would lead to the final showdown at Zama in 202 BC. The Great Plains had been the turning point. On an expanse of Tunisian farmland that has long since been plowed over, Scipio proved that Carthage could no longer protect its own territory. The mercenaries who died there, surrounded and cut off in a land they did not know, paid the ultimate price for Carthage's failure to build an army of its own citizens.