The second slave revolt was a consequence of
Marius' need for soldiers
Strange love affair
Of course there weren't just three slave revolts. Diodorus Siculus speaks of many revolts.
First Diodurus tells us a story about a strange kind of revolt:
In Capua young noble Titus Minucius Vettius with a rich father, fell in love with a beautiful slave girl. But the girl was not his property. He bought her from her reluctant owner for the outrages sum of seven attic talents When he, after several delays, couldn't pay the money, he bought arms and shields. Again he bargained a delayed payment. He armed his slaves and started raiding the neighboring farmsteads.
Titus Vettius betrayed
The Roman senate sent Lucius Lucullus with an army of about 4000 men. Titus now had about 3500 men and Apollonius was his general. The slave army at first had the upper hand but Lucullus promised Apollonius immunity for punishment if he betrayed Titus, which he did and the boy took his own life.
In the course of Marius' campaign against the Cimbri the senate granted Marius permission to summon military aid from the nations situated beyond the seas. Accordingly Marius sent to Nicomedes, the king of Bithynia, requesting assistance. The king replied that the majority of the Bithynians had been seized by tax farmers and were now in slavery in the Roman provinces. The senate then issued a decree that no citizen of an allied state should be held in slavery in a Roman province, and that the praetors should provide for their liberation. In compliance with the decree Licinius Nerva, who was at this time governor of Sicily, appointed hearings and set free a number of slaves, with the result that in a few days more than eight hundred persons obtained their freedom. And all who were in slavery throughout the island were agog with hopes of freedom. The notables, however, assembled in haste and entreated the praetor to desist from this course.
Licinius Nerva gives in
Licinius gave in and started to sent slaves requesting their freedom back to their masters. These slaves banded together. Near Syracuse a slave called Varius murdered his masters and with the other slaves of that property he started raiding on the other farms. He too brought together an army but he too was betrayed and killed.
More slave revolts
This was not the end of it though. The next slave revolt started soon after the praetor had disbanded his troops and hesitated to act. The slaves chose Salvius as their leader. He was skilled in divination and a flute-player. When the praetor did attack he was defeated by the rebels. His troops were routed and many killed. The rebels gained many weapons. Salvius divided his men in three parties and had them raid and scour the country. When he reunited his troops, there were 2000 cavalry and 20,000 infantry. Then he attacked the city of Morgantina (now an exhumation site). Here the praetor, Lucinius Nerva, attacked the rebels again and lost for the second time many of his men. Salvius was undisputed master of the open country and now started to besiege Morgantina.
Athenion starts a slave revolt of his own
Slave with a lamp
At last Roman counter measures
Salvius, after he conquered Morgantina now wanted to seize Triocala He summoned Athenion to come to Triocale. Surprisingly Athenion obeyed and accepted the role of general. Salvius, who now called himself Tryphon, made Triocala his stronghold. The Roman senate now sent Lucius Licinius Lucullus with an army of 17,000 to oppose the rebels. On learning that Lucullus was approaching Tryphon first decided to stay in the stronghold, but Athenion convinced him to fight in the open. They lost that battle an returned to Triocala.
Luculus achieved nothing more than that one victory and was replaced by Gaius Servilius who likewise achieved nothing. Athenion who had taken Tryphon's place after the latter had died, not hindered by Servilius laid cities under siege and moved over the island freely.