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
All these pieces of evidence speak clearly enough; but, even were it not so, the desperate position of the democracy in presence of the military power--which since the Gabinio-Manilian laws assumed by its side an attitude more threatening than ever--renders it almost a certainty that, as usually happens in such cases, it sought a last resource in secret plots and in alliance with anarchy. The circumstances were very similar to those of the Cinnan times. While in the east Pompeius occupied a position nearly such as Sulla then did, Crassus and Caesar sought to raise over against him a power in Italy like that which Marius and Cinna had possessed, with the view of employing it if possible better than they had done.
The way to this result lay once more through terrorism and anarchy, and to pave that way Catilina was certainly the fitting man. Naturally the more reputable leaders of the democracy kept themselves as far as possible in the background, and left to their unclean associates the execution of the unclean work, the political results of which they hoped afterwards to appropriate. Still more naturally, when the enterprise had failed, the partners of higher position applied every effort to conceal their participation in it. And at a later period, when the former conspirator had himself become the target of political plots, the veil was for that very reason drawn only the more closely over those darker years in the life of the great man, and even special apologies for him were written with that very object.(21)
21. Such an apology is the -Catilina- of Sallust, which was published by the author, a notorious Caesarian, after the year 708, either under the monarchy of Caesar or more probably under the triumvirate of his heirs; evidently as a treatise with a political drift, which endeavours to bring into credit the democratic party-- on which in fact the Roman monarchy was based--and to clear Caesar's memory from the blackest stain that rested on it; and with the collateral object of whitewashing as far as possible the uncle of the triumvir Marcus Antonius (comp. e. g. c. 59 with Dio, xxxvii. 39). The Jugurtha of the same author is in an exactly similar way designed partly to expose the pitifulness of the oligarchic government, partly to glorify the Coryphaeus of the democracy, Gaius Marius. The circumstance that the adroit author keeps the apologetic and inculpatory character of these writings of his in the background, proves, not that they are not partisan treatises, but that they are good ones.
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Reference address : https://www.ellopos.net/elpenor/rome/5-05-parties-pompeius.asp?pg=46