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.