The First Punic War had begun in 264 BC over control of the Sicilian town of Messana. By 256 BC, years of stalemate on Sicily -- where Carthaginian coastal cities could be resupplied by sea faster than Roman legions could besiege them -- convinced Rome to try something audacious. Using a shipwrecked Carthaginian quinquereme as a blueprint, the Romans had built an entire navy. After defeating the Carthaginian fleet at the Battle of Cape Ecnomus in a clash of roughly 680 warships carrying up to 290,000 men, Regulus landed in Africa near Aspis on the Cape Bon Peninsula. His forces ravaged the countryside, captured 20,000 enslaved people, and seized vast herds of cattle. Then the Senate recalled most of the fleet and army to Sicily, leaving Regulus with a fraction of his original force to hold Roman gains through the winter.

When the Carthaginians advanced to relieve Adys, they fortified a rocky hilltop overlooking the town. Their army was roughly equal to the Roman force in size but far superior in cavalry and war elephants -- advantages that, as Polybius pointed out, were utterly wasted behind fortifications on broken terrain. Modern historians have been kinder to the Carthaginian generals, noting that their army was newly assembled and untested, making a cautious hilltop position defensible logic. But Regulus did not give them time to reconsider. He split his army in two and ordered both columns to execute a night march, converging on the camp for a twin assault at dawn.

The attacks launched at first light, though not quite simultaneously. Complete surprise proved impossible -- the Carthaginians managed to form up and meet one Roman column, driving it back down the slope in disorder. For a moment the battle hung in the balance. But the pursuing Carthaginians overextended, chasing their retreating enemy off the hill and exposing their rear. The second Roman column, rather than storming the camp as planned, swung downhill and crashed into the backs of the now-strung-out Carthaginian pursuers. Caught between two forces, the Carthaginians broke. According to the military historian Nigel Bagnall, the cavalry and elephants had already been evacuated, recognized as useless on the rocky terrain. The Carthaginians in the camp -- whose fortifications had never been breached -- panicked at the sight of their comrades fleeing and abandoned their position. The Romans plundered the hilltop camp at their leisure.

Regulus pressed his advantage with devastating speed. He captured Tunis, just 16 kilometers from Carthage, and began raiding the outskirts of the city itself. Carthage's African subjects revolted. Refugees packed the capital, and food ran short. The Carthaginians sued for peace. But Regulus, smelling total victory, offered terms so punishing they amounted to unconditional surrender: hand over Sicily, Sardinia, and Corsica; pay all Roman war expenses; accept a navy limited to a single warship. The Carthaginians chose to fight on. They hired a Spartan mercenary commander named Xanthippus, who retrained their army over the winter and led them to crushing victory at the Battle of the Bagradas River in spring 255 BC. Of Regulus's 15,500 men, approximately 13,000 were killed. Regulus himself was captured. The war continued for another 14 years.