The mercenary leader and skilled polyglot orator Autaritus is cited by Polybius as a chief instigator of this massacre. Hamilcar, in turn, killed his prisoners. From this point, neither side showed any mercy, and the unusual ferocity of the fighting caused Polybius to term it the "Truceless War". Any further prisoners taken by the Carthaginians were trampled to death by elephants. At some point between March and September 239 BC the previously loyal cities of Utica and Hippo slew their Carthaginian garrisons and joined the rebels. The people of Utica offered their city to the Romans, who, consistent with their response to the mutineers on Sardinia, declined. The rebels previously operating in the area moved south and laid siege to Carthage. Having a clear superiority in cavalry, Hamilcar raided the supply lines of the rebels around Carthage. In mid-239 BC, he was joined by Hanno and his army, but the two men disagreed as to the best strategy and operations were paralysed. Unusually, the choice of supreme commander was put to a vote of the armypossibly only the officersand Hamilcar was elected; Hanno left the army. In early 238 BC the lack of supplies forced the rebels to lift the siege of Carthage. They fell back to Tunis, from where they maintained a more distant blockade. While Matho maintained the blockade, Spendius led 40,000 men against Hamilcar. As in the previous year, they stayed to the higher and rougher terrain and harassed the Carthaginian army. After a period of campaigning, the details of which are not clear in the sources, Hamilcar trapped the rebels in a pass or mountain range known as the Saw. Pinned against mountains and with their food exhausted, the rebels ate their horses, their prisoners and then their slaves, hoping that Matho would sortie from Tunis to rescue them. Eventually, the surrounded troops forced their leaders to parley with Hamilcar, but on a thin pretext, he took Spendius and his lieutenants prisoner. The rebels then attempted to fight their way out in the Battle of the Saw and were massacred to a man. Hamilcar then marched on Tunis and laid siege to it in late 238 BC. The city was difficult to access from both the east and the west, so Hamilcar occupied a position to the south with half the army, and his deputy Hannibal was to the north with the balance. The rebel leaders