A second army was assembled in Carthage and entrusted to Hamilcar, who had commanded Carthaginian forces on Sicily for the last six years of the First Punic War.

Rebel armies commanded by Spendius, from both the Utica siege and a camp guarding the only bridge over the lower Bagradas River, marched towards the Carthaginians.

[1] While the war with Rome was being fought on Sicily, the Carthaginian general Hanno led a series of campaigns that greatly increased the area of Africa controlled by Carthage.

He extended its control to Theveste (modern Tébessa, Algeria) 300 kilometres (190 mi) south-west of their capital[2][3] and was rigorous in squeezing taxes out of the newly conquered territory to pay for both the war with Rome and his own campaigns.

[6][7] The Carthaginian Senate ordered the commander of its forces on Sicily, Hamilcar Barca, to negotiate a peace treaty on whatever terms he could.

[11] 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.

Gisco, who had a good reputation with the army, was brought over from Sicily in late 241 BC and despatched to the camp with enough money to pay most of what was owed.

[12][13][14] The rebels declared Spendius, an escaped Roman slave who faced death by torture if recaptured, and Mathos, a Berber dissatisfied with Hanno's attitude towards tax-raising from Carthage's African possessions, their generals.

[15] 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.

[5][24] The rebels reinforced their siege of Utica to 15,000 men, where Spendius took command and continued to restrict landward access to Carthage from their stronghold at Tunis.

[note 2] This was too deeply submerged to be fordable under normal conditions, but Hamilcar was aware that when the wind blew strongly from the east it held back the flow of the Bagradas sufficiently for the sandbar to be crossable.

[28] With a strong easterly wind blowing, Hamilcar marched his army out of Carthage at night in great secrecy along the north shore of the isthmus towards the mouth of the Bagradas River.

His movement was not detected by the rebels and at dawn he crossed the Bagradas River along the sandbar – the army had marched 16 km from Carthage and was now free to manoeuvre in the African countryside.

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

[32][33] 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.

[42] Much of the Carthaginian army was newly recruited, but Hamilcar had been able to train it in some drill and basic battlefield manoeuvres before they left Carthage.

[46] The modern historian Dexter Hoyos stresses that "[s]uch manoeuvres were about the simplest that any army could learn, once it mastered the absolute basics of marching in formation".

[46] The leading rebel formation suddenly found itself not pursuing a shaken foe, but faced at close range by formed bodies of elephants and cavalry with more than 7,000 heavy infantry advancing behind them.

At least part of this body was obstructed by the other rebel formation which was still charging towards the Carthaginians and they even came to blows as the men of the second group attempted to prevent those of the first from fleeing.

[49] While Hanno manoeuvred against Mathos to the north near Hippo, Hamilcar confronted several towns and cities that had gone over to the rebels, bringing them back to Carthaginian allegiance with varying mixtures of diplomacy and force.

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

[50][51] South west of Utica Hamilcar moved his force into the mountains in an attempt to bring the rebels to battle,[5] but was surrounded.

The Carthaginians were only saved from destruction when a Numidian leader, Naravas, who had served with and admired Hamilcar in Sicily, swapped sides with his 2,000 cavalry.

[55] The Carthaginians fought a fierce and bitter campaign against the rebels, before wearing them down and finally defeating them at the Battle of Leptis Parva in 238 BC.