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
But as the upper course of the river was in the hands of Hannibal, he could not be prevented from marching up the stream, crossing on a bridge of boats, and in a few days confronting the Roman army on the right bank. The latter had taken a position in the plain in front of Placentia; but the mutiny of a Celtic division in the Roman camp, and the Gallic insurrection breaking out afresh all around, compelled the consul to evacuate the plain and to post himself on the hills behind the Trebia.
This was accomplished without notable loss, because the Numidian horsemen sent in pursuit lost their time in plundering, and setting fire to, the abandoned camp. In this strong position, with his left wing resting on the Apennines, his right on the Po and the fortress of Placentia, and covered in front by the Trebia--no inconsiderable stream at that season--Scipio was unable to save the rich stores of Clastidium (Casteggio) from which in this position he was cut off by the army of the enemy; nor was he able to avert the insurrectionary movement on the part of almost all the Gallic cantons, excepting the Cenomani who were friendly to Rome; but he completely checked the progress of Hannibal, and compelled him to pitch his camp opposite to that of the Romans.
Moreover, the position taken up by Scipio, and the circumstance of the Cenomani threatening the borders of the Insubres, hindered the main body of the Gallic insurgents from directly joining the enemy, and gave to the second Roman army, which meanwhile had arrived at Ariminum from Lilybaeum, the opportunity of reaching Placentia through the midst of the insurgent country without material hindrance, and of uniting itself with the army of the Po.
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Reference address : https://www.ellopos.net/elpenor/rome/3-05-war-hannibal-cannae.asp?pg=6