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
Failure of the First Plans of Conspiracy
In December 688--so we are told--the leaders of the league thought that they had found the fitting occasion for striking a blow. The two consuls chosen for 689, Publius Cornelius Sulla and Publius Autronius Paetus, had recently been judicially convicted of electoral bribery, and therefore had according to legal rule forfeited their expectancy of the highest office. Both thereupon joined the league. The conspirators resolved to procure the consulship for them by force, and thereby to put themselves in possession of the supreme power in the state. On the day when the new consuls should enter on their office--the 1st Jan. 689-- the senate-house was to be assailed by armed men, the new consuls and the victims otherwise designated were to be put to death, and Sulla and Paetus were to be proclaimed as consuls after the cancelling of the judicial sentence which excluded them.
Crassus was then to be invested with the dictatorship and Caesar with the mastership of the horse, doubtless with a view to raise an imposing military force, while Pompeius was employed afar off at the Caucasus. Captains and common soldiers were hired and instructed; Catilina waited on the appointed day in the neighbourhood of the senate- house for the concerted signal, which was to be given him by Caesar on a hint from Crassus. But he waited in vain; Crassus was absent from the decisive sitting of the senate, and for this time the projected insurrection failed.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/5-05-parties-pompeius.asp?pg=17