Slaves were trained as gladiators, and in 73 BC such a slave, a Thracian named Spartacus, broke out of a gladiator training camp at Capua and took refuge in the hills. The number of his band swelled rapidly and he kept his men well in hand and under strict discipline and routed two commanders who were sent to capture him. In 72 BC Spartacus had so formidable force behind him, that two consular armies were sent against him, both of which he destroyed.
Pompey was in the west, Lucullus in the east. It was Crassus who at the head of six legions at last brought Spartacus to bay, shattered his army, and slew him on the field (71 BC).
Five thousand of Spartacus' men cut their way through the lines and escaped but only to end up in the very path of Pompey's army returning from Spain.