During the siege of Tunis in October 238 BC a rebel army under Mathos was besieged by a Carthaginian force under Hamilcar Barca and Hannibal.

At the northern camp, commanded by his subordinate Hannibal, he had the ten captured rebel leaders tortured to death and their bodies crucified before returning to his own base to the south of Tunis.

[3] While the war with Rome was being played out, the Carthaginian general Hanno led a series of campaigns that greatly increased the area of Africa controlled by Carthage.

[4] Across the Carthaginian possessions in Africa, half of all agricultural output was taken as war tax, and the tribute previously due from towns and cities was doubled.

[7][8] Freed of their long period of military discipline and with nothing to do, the men grumbled among themselves and refused all attempts by the Carthaginians to pay them less than the full amount due.

Several soldiers insisted that no deal with Carthage was acceptable, a riot broke out, dissenters were stoned to death, the Carthaginian negotiators were taken prisoner and their treasury was seized.

[9][10][11] Spendius, an escaped Roman slave who faced death by torture if he were recaptured, and Mathos, a Berber dissatisfied with Hanno's attitude towards tax raising from Carthage's African possessions, were declared generals by the rebellious soldiers.

The news of a formed, experienced, anti-Carthaginian army in the heart of its territory spread rapidly and many cities and towns rose in rebellion.

Provisions, money and reinforcements poured in; eventually an additional 70,000 men according to the ancient Roman historian Polybius, although many would have been tied down in garrisoning their home towns against Carthaginian retribution.

Roman sources refer to these foreign fighters derogatively as "mercenaries", but the historian Adrian Goldsworthy describes this as "a gross oversimplification".

[17][18] Both Spain and Gaul provided experienced infantry – unarmoured troops who would charge ferociously, but had a reputation for breaking off if a combat was protracted.

It included deserters from the rebels, 2,000 cavalry and 70 elephants, and was placed under the command of Hamilcar Barca,[note 3] who had previously led the Carthaginian forces in Sicily.

He was shadowed by a superior-sized rebel force under Spendius, which kept to rough ground for fear of the Carthaginians' cavalry and elephants, and harried his foragers and scouts.

[36] Since leaving Carthage, Hamilcar had treated rebels he had captured well and offered them a choice of joining his army or free passage home.

To remove the possibility of any goodwill between the sides, he had 700 Carthaginian prisoners tortured to death: they had their hands cut off, were castrated, their legs broken, and were then thrown into a pit and buried alive.

From this point, neither side showed any mercy, and the unusual ferocity of the fighting caused the near-contemporary historian Polybius to term it the "Truceless War".

[38][39] At some point between March and September 239 BC the previously loyal cities of Utica and Hippo killed their Carthaginian garrisons and joined the rebels.

In early 238 BC the lack of supplies forced Mathos to lift the close siege of Carthage; he maintained a more distant blockade from Tunis.

Trapped in the mountains and with their food exhausted, the rebels ate their horses, their prisoners and then their slaves, hoping Mathos would sortie from Tunis to rescue them.

[41][42] After their victory at the Saw the Carthaginians marched on the main rebel force at Tunis around October 238 BC, accepting the surrender of many towns and villages on the way.

Hamilcar kept his force at a high state of readiness, in case of a rebel assault, but Hannibal was more confident and laxer in ensuring that his men were effective in their patrols and sentry duties.

The Carthaginians suffered heavy casualties in dead and captured and lost all of their baggage and most of their troops' weapons, armour and personal equipment.

[47] Hanno and Hamilcar marched after the rebels with an army totalling more than 25,000 men, including every Carthaginian citizen of military age,[49] and many war elephants.