The Barcid Revolt (250-248 BC)
As the hostilities between Rome and Carthage ended and their fleets and armies returned home, Carthage was burdened with the additional cost of having to discharge its mercenary forces. They numbered nearly 20,000 at the end of the war, and Carthage had very nearly been crippled by the costs of the war. However, Carthage was not so destitute that they could not afford to pay their former army at all. The issue was how quickly to do so, and how much of their agreed upon payment should the mercenaries receive at once.
Hanno, one of Carthage's leading generals, was tasked with the duty of discharging the mercenaries, and he worked with the contingents in as small numbers as he possibly could divide them, offering them reduced payments if they would accept now, arguing that the indemnity owed to Rome would slow Carthage's ability to pay them in full. They were welcome to sit in camp and wait for their full payment later, if they so wished. These negotiations started off well, and Hanno was gradually winnowing down the army to a less dangerous size. Always there was a risk that some of the mercenaries would violently refuse the new terms and take up their arms against Carthage, so Hanno proceeded carefully and as diplomatically as possible.
Eventually, however, many of the mercenary bands grew disatisfied with Hanno’s handling of their discharges, and saw it, not unreasonably, as simply an attempt by the Carthaginians to welch on their contracted rates. These mercenaries, represented by one of their generals, a Gallic soldier named Autaritus, began to protest their treatment by Carthage and advocate strongly for their agreed upon contract rates. Nor were these dissident mercenaries without sympathizers among the Carthaginian elite, for not all felt that they should have agreed to Rome’s humiliating peace treaty. Such sentiment only grew now that Rome’s army had departed their homeland.
This revanchist faction among the Carthaginians counted among their number one young officer by the name of Hamilcar Barca. Hamilcar was far from influential enough to be considered a leader of the faction, but he had already proven himself a skilled commander and had developed close ties with many of the mercenary commanders. He took up their cause before the Carthaginian state and advocated honoring their contracts, rather than haggling them downward after the fact. Far better, he argued, to pay in good faith the men that had fought for Carthage, than to pay the Romans that attacked their home.
Bust of Hamilcar Barca
His efforts did not go unrewarded, but the Carthaginian Senate only agreed to increase their starting offers, not to honor the full contracts immediately. They made a show of diverting some of their payments to Rome, to demonstrate the impossible situation they were in, but the mercenaries were hardly sympathetic. They largely accepted the better rate offered, and many looked to Hamilcar as their friend in Carthage, while the Romans took some note of this trouble-maker.
Thus, Carthage avoided angering their former army too greatly, and secured a few years of peace. As they rebuilt after the war, however, the revanchist faction grew stronger, and Hamilcar’s star was in the ascent among those that sought to avenge their defeat. He was able to secure the support of several mercenary bands, and, in 250 BC, attempted to instigate a war with the nearby Numidians, hoping that doing so would force a conflict with Rome.
In both regards, Hamilcar failed, as the Numidians did not attempt to counter his actions through military force, but by contacting the Carthaginian Senate itself. Hamilcar was ordered to present himself for judgement, but those that wanted him arrested and eliminated had underestimated his popularity with the people. Hamilcar’s associates in the city stirred up a series of revolts, and soon the city of Carthage was effectively embroiled in a civil war, not half a decade removed from their defeat at the hands of the Romans.
The faction that had coalesced around Hamilcar Barca's instigations came to be known as the Barcids, as even though he was not the sole leader of that faction, he was by far the most notorious. He was able to bring many mercenaries to his side in the conflict, based on his reputation for dealing with them fairly, and many regarded his chance of victory favorably. Some even hoped that he would honor the back pay due to them after the Punic War, after his faction won. Though the Barcid forces were larger, the Carthaginian Senate was able to secure the city before Hamilcar could reach it, and though many of the mercenaries that Carthage relied upon for an army sided with Hamilcar, the walls were garrisoned and the navy remained loyal to the Senate.
The Barcids laid siege to Carthage, largely waiting for sympathizers to enable them to bypass the defenses, but the opportunity did not arrive before Rome took an interest in the situation. Hamilcar was hopeful when he learned that the Romans were responding to his actions, certain that a Roman army on Carthaginian soil so soon after the recent war would stir up more resentment against Rome and the Senate that he considered to be their puppets. However, the Romans did not send an army, but they did send material support for the Senate, dispatching their own fleet and food and other supplies to the city, and even offered a gift of one year's worth of Carthage's annual tribute to the Senate.
This support enabled the Carthaginian Senate to entice some of the mercenaries in the Barcid faction to defect and a few others to simply abandon the conflict entirely and look for other clients. Hamilcar still had a numerical advantage, but it had been greatly reduced, and the Senate had sought out the leadership of Xanthippos once more. Xanthippos was able to convert a portion of the remaining mercenaries in the Barcid camp, and the Barcids realized that their moment had passed. Other leaders began to defect back to the Senate's side, and soon, Hamilcar was the only rebel leader remaining defiant.
Surrender was not an option for Hamilcar, as he had been declared an enemy of the state, and the only fate left for him was crucifixion. Still in command of enough of an army to be dangerous, Hamilcar surveyed his options. His ultimate course was to flee west with his army. Initially, he apparently considered taking some of the outlying Punic cities in North Africa and use those as bases of operations against the Senatorial forces. However, that was a losing proposition, all of his ambitions had required a quick victory before Carthage could be truly weakened by his revolt. All was not entirely lost, however, as one Carthaginian colony had defected to the Barcid faction. Ironically, it was the last outpost in Hispania that had remained loyal to Carthage, Gades (in Punic, Gadir).
Gades was far from the center of Carthaginian power, but Hamilcar knew that Hispania was full of wealth waiting for those that would take it. He decided to relocate to Gades with his army and his companions, and hoped that, from there, he might carve out a destiny greater than the ignominious death that the Carthaginian Senate had in store for him. Some in the city thought it was best to hound him as he fled, but when it became known that his forces were fleeing all the way to distant Gades, the consensus was that it was best to allow him to flee into effective exile. Hispania was all but lost anyway, and was far from matters of import.
So it was that Hamilcar arrived in Gades in 248 BC, and took control of the city. He established a government-in-exile of sorts, and decided that he would restore Carthaginian authority in Hispania, even if such authority would be entirely independent of - and hostile to - the actual Carthaginian government. Hamilcar was the undisputed leader of this rival government, though it retained the nominal republican forms of Carthage's own government.
Afterword
I really enjoy the idea that Carthaginian Spain, under the Barcids, was basically an independent kingdom, historically, that only paid nominal lip service to the idea that the Barcid forces were operating on behalf of the actual Carthaginian government. I've also been listening to the Revolutions' podcast series on the Mexican Revolution, and I thought it might be interesting if, after being humiliated by Rome, some Carthaginians might want to pull a Poncho Villa: instigate a war with an outside enemy, in order to get everyone in the homeland united against that enemy. It only sort of worked for Villa, and it totally backfires when Hamilcar tries it.
This also ends up working out as a 'great sorting' of kinds for the Carthaginians. Those that hate Rome the most? They're in Gades. Those that are willing to work with the new status quo that has them as a client state of Rome? They're in Carthage. As for Rome supporting Carthage in their little civil war, this is basically what Rome did during the Mercenary War, historically. They continually rebuffed the rebels at every turn, released Carthagians without ransom, and generally tried to help Carthage out from the side lines - and then they changed their minds and took Sardinian and Corsica from Carthage just for the hell of it. Here, I figure Rome already has all the land they want from Carthage, and Carthage is a client state of theirs, so they'll be just a bit more pro-Carthage while it deals with an analogue to the Mercenary War.