At the start of 72 BC, the formidable slave army of was Spartacus split into two forces. His part began the long march north to cross the Alps into freedom. Crixus, the commander of the second part of the army, stupidly failed to realize that the small victories they enjoyed were against under prepared and disinterested opponents. He stayed in southern Italy looting and pillaging to their hearts' content. After Spartacus and Crixus defeated the hastily recruited praetorian forces in 73 BC, however, the Senate reacted with a bit more enthusiasm.
Two Consular armies and perhaps additional lesser forces were dispatched to deal with what was becoming a real threat. One force, under either the Consul Gellius or Q. Arrius the newly appointed governor of Sicily en route to his province, met up with Crixus at Mt. Garganus. With 3,000 Germanics split from the main force of Spartacus, Crixus and his small army were rounded up and utterly destroyed.
Spartacus meanwhile was moving north, apparently with the intention of crossing the Alps into non-Roman territory. One Consul, Gneaus Cornelius Lentulus barred the gladiator's path while Gellius pursued. Hoping to crush Spartacus between them, the plan seemed to be working. Spartacus had little choice but to continue marching right into Lentulus, and did so with spectacular results. First Spartacus defeated Lentulus, then turned and did the same to Gellius in turn. Continuing to march north, the slave army then met with the Proconsular governor of Cisalpine Gaul, Cassius Longinus. Once again Spartacus and his misfit army turned out the victor. In retaliation for the death of Crixus, and perhaps for his own tenure as a Roman slave, Spartacus had 300 pairs of Roman prisoners fight as gladiators to the death. Clearly Spartacus, as has been popularly depicted, had no concern over the state of slavery or the gladiator games in the Roman world. He simply wished freedom for himself and any who joined him, not the complete social reform of the Roman system.
The very successes of their army against Roman legions may have been their undoing. Spartacus wished to continue north to relative freedom from Roman interference, but victories, with the confidence and plunder they provided, had a powerful effect. Many of the Germanics and Gauls wished to stay in Italy and reap the rewards of their success. Rather than escape himself with a smaller army, Spartacus, either with visions of grandeur himself, or feeding off the power of a large force, next turned south. Some have suggested Rome itself was the target, but a rendezvous with Cilician pirates seems a more likely course. If they would not cross the Alps, his army may have been willing to cross to Sicily or even Africa as an alternative.
Nevertheless, Spartacus and his army that had swelled to 120,000 men did move south. In the mountains near Thurii, they set up camp and gained much supply from local trade and plunder from raids. Equipping themselves into an appropriate military force, the slave army had grown from a minor nuisance to a formidable and legitimate power. The Senate, now facing this power, as it easily won victory after victory, looked to an experienced commander to deal with the threat. The current Consular commanders were withdrawn and the Propraetor Marcus Licinius Crassus was appointed to the special command. Crassus too command with 6 new legions and the four remaining veteran legions, making it quite apparent that Spartacus was considered a serious threat.