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
Renewed Outbreak of the Spanish Insurrection - Metellus Sent to Spain
Sertorius, who twenty years before had served under Titus Didius in Spain and knew the resources of the land, resolved to comply with the invitation, and, leaving behind a small detachment on the Mauretanian coast, embarked for Spain (about 674). The straits separating Spain and Africa were occupied by a Roman squadron commanded by Cotta; to steal through it was impossible; so Sertorius fought his way through and succeeded in reaching the Lusitanians. There were not more than twenty Lusitanian communities that placed themselves under his orders; and even of "Romans" he mustered only 2600 men, a considerable part of whom were deserters from the army of Pacciaecus or Africans armed after the Roman style.
Sertorius saw that everything depended on his associating with the loose guerilla-bands a strong nucleus of troops possessing Roman organization and discipline: for this end he reinforced the band which he had brought with him by levying 4000 infantry and 700 cavalry, and with this one legion and the swarms of Spanish volunteers advanced against the Romans. The command in Further Spain was held by Lucius Fufidius, who through his absolute devotion to Sulla--well tried amidst the proscriptions--had risen from a subaltern to be propraetor; he was totally defeated on the Baetis; 2000 Romans covered the field of battle.
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Reference address : https://www.ellopos.net/elpenor/rome/5-01-lepidus-sertorius.asp?pg=26