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
It was threatened with a day like the 20th July 365 u. c. or the 15th June 455 a. d.-- the days of the Celts and the Vandals. The time was gone by when a coup de main against Rome was a foolish enterprise, and the assailants could have no want of connections in the capital. The band of volunteers which sallied from the city, mostly youths of quality, was scattered like chaff before the immense superiority of force. The only hope of safety rested on Sulla. The latter, on receiving accounts of the departure of the Samnite army in the direction of Rome, had likewise set out in all haste to the assistance of the capital.
The appearance of his foremost horsemen under Balbus in the course of the morning revived the sinking courage of the citizens; about midday he appeared in person with his main force, and immediately drew up his ranks for battle at the temple of the Erycine Aphrodite before the Colline gate (not far from Porta Pia). His lieutenants adjured him not to send the troops exhausted by the forced march at once into action; but Sulla took into consideration what the night might bring on Rome, and, late as it was in the afternoon, ordered the attack. The battle was obstinately contested and bloody.
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Reference address : https://www.ellopos.net/elpenor/rome/4-09-cinna-sulla.asp?pg=49