Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
In the district between Enna and Leontini (Lentini) where these bands had their head-quarters, the open country was wholly in the hands of the insurgents and Morgantia and other walled towns were already besieged by them, when the Roman governor with his hastily-collected Sicilian and Italian troops fell upon the slave-army in front of Morgantia.
He occupied the undefended camp; but the slaves, although surprised, made a stand. In the combat that ensued the levy of the island not only gave way at the first onset, but, as the slaves allowed every one who threw down his arms to escape unhindered, the militia almost without exception embraced the good opportunity of taking their departure, and the Roman army completely dispersed.
Had the slaves in Morgantia been willing to make common cause with their comrades before the gates, the town was lost; but they preferred to accept the gift of freedom in legal form from their masters, and by their valour helped them to save the town--whereupon the Roman governor declared the promise of liberty solemnly given to the slaves by the masters to be void in law, as having been illegally extorted.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/4-04-rule-restoration.asp?pg=21