), a considerable river of Gallia Cispadana, falling into the Padus about 2 miles W. of Placentia. From its proximity to the latter city Pliny designates it as “Trebias Placentinus.” (Plin. Nat. 3.16. s. 20
; Strab. v. p.217
It has its sources in the Ligurian Apennines near Montebruno,
and has a course of above 50 miles from thence to the Po.
Throughout the greater part of this course it flows through a mountain valley, passing under the walls of Bobbio
(celebrated in the middle ages for its convent, from which some of the most valuable MSS. of ancient authors have been derived), and does not emerge from the hills which form the underfalls of the Apennines till within about 12 miles of its mouth. For the remainder of its course it flows through the fertile plain of the Padus, and crosses the Via Aemilia about 3 miles W. of Placentia.
It appears probable that the Trebia was fixed by Augustus as the western limit of the Eighth Region, and continued from that period to be regarded as the limit of Gallia Cispadana towards Liguria.
This is not distinctly stated, but may probably be inferred from the circumstance that Placentia was situated in the Eighth Region, while Iria (Voghera
), the next town to the W., was certainly in Liguria. (Plin. Nat. 3.5. s. 7
. s. 20.) Like most of the rivers which flow from the Apennines, the Trebia varies very much according to the season: in summer it is but a scanty stream, winding through a broad bed of stones, but in winter and after heavy rains it becomes a formidable torrent.
The chief celebrity of the Trebia is derived from the battle which was fought on its banks in B.C. 218 between Hannibal and the Roman consul Sempronius, and which was the first of the decisive victories obtained by the Carthaginian general. Unfortunately the movements which preceded and led to this battle, and the exact site on which it occurred, are very difficult to determine. Scipio after his defeat on the Ticinus had recrossed the Padus and withdrawn to Placentia, where the presence of a Roman colony afforded him a secure stronghold. Hannibal on the other hand effected his passage of the Padus higher up, above its junction with the Ticinus, and then advanced along the right bank of the river, till he approached Placentia, and established his camp within 5 miles of that of Scipio. (Pol. 3.66.)
The defection of the Boian Gauls having soon after given the alarm to Scipio, he broke up his camp and withdrew “to the hills that bordered the river Trebia.” (Ib.
In this movement, it is clear, from what we are told immediately afterwards that, he crossed
the river Trebia (Ib.
68): his former camp therefore, though in the neighbourhood of Placentia, must have been on the W. side of the Trebia.
In this new position, which was one of considerable natural strength (Ib.
67), Scipio awaited the arrival of Sempronius with his army, who was advancing from Ariminum, and succeeded in effecting a junction with his colleague, without opposition from Hannibal. (Ib.
The attention of the Carthaginian general had been apparently drawn off [p. 2.1224]
to the W.; where the town of Clastidium was betrayed into his hands. Meanwhile Sempronius, who was newly arrived, after a short interval of repose, was eager for a general engagement, and his confidence was increased by a partial success in a combat of cavalry, in the plain between the Trebia and the Padus (Ib.
69.) Hannibal, who on his side was equally desirous of a battle, took advantage of this disposition of Sempronius, and succeeded in drawing him out of his camp, where he could not venture to attack him, into the plain below, which was favourable to the operations of the Carthaginian cavalry and elephants. For this purpose he sent forward a body of Numidian horse, who crossed the Trebia and approached the Roman camp, but, as soon as a body of Roman cavalry and light-armed troops were sent out against them, retreated skirmishing until they had recrossed the river. Sempronius followed with his whole army, and crossed the Trebia, not without difficulty, for the river was swollen with late rains, and was only just fordable for the infantry. His troops suffered severely from cold and wet, and when the two armies met in order of battle, early began to feel themselves inferior to the enemy: but the victory was decided by a body of 1000 foot and 1000 horse, under the command of Mago, the brother of Hannibal, which had been placed by that general in ambuscade, in the hollow bed of a stream which crossed the field of battle, and by a sudden onset on the rear of the Roman army, threw it into complete confusion.
A body of about 10,000 Roman infantry succeeded in forcing their way through the centre of the enemy's line, but finding themselves isolated, and their retreat to their camp quite cut off, they directed their march at once towards Placentia, and succeeded in reaching that city in safety.
The other troops were thrown back in confusion upon the Trebia, and suffered very heavy loss in passing that river; but those who succeeded in crossing it, fell back upon the body already mentioned and made good their retreat with them to Placentia. Thither also Scipio on the following day repaired with that part of the Roman forces which had not been engaged in the battle. (Pol. 3.70--74.)
From the view above given of the battle and the operations that preceded it, which coincides with that of General Vaudoncourt (Campagnes d'Annibal en Italie,
vol. i. pp. 93--130), it seems certain that the battle itself was fought on the left
bank of the Trebia, in the plain, but a short distance from the foot of the hills; while the Roman camp was on
the hills, and on the right bank of the Trebia.
It is certain that this view affords much the most intelligible explanation of the operations of the armies, and there is nothing in the narrative of Polybius (which has been exclusively followed in the above account) inconsistent
with it, though it must be admitted that some difficulties remain unexplained. Livy's narrative on the contrary is confused, and though based for the most part on that of Polybius, seems to be mixed up with that of other writers. (Liv. 21.52
.) From his account of the retreat of the Roman army and of Scipio to Placentia after the battle, it seems certain that he considered the Roman camp to be situated on the left bank of the river, so that Scipio must necessarily cross it in order to arrive at Placentia, and therefore he must have conceived the battle as fought on the right bank: and this view has been adopted by many modern writers, including Niebuhr and Arnold; but the difficulties in its way greatly exceed those which arise on the contrary hypothesis. Niebuhr indeed summarily disposes of some of these, by maintaining, in opposition to the distinct statements of Polybius, that Hannibal had crossed the Padus below Placentia, and that Sempronius joined Scipio from Genua and not from Ariminum. Such arbitary assumptions as these are worthless in discussing a question, the decision of which must rest mainly, if not entirely, on the authority of Polybius. (Niebuhr's Lectures on Roman History
vol. ii. pp. 94--96; Arnold, Hist. of Rome,
vol. iii. pp. 94--101.) Cramer adopts the views of General Vaudoncourt. (Anct. Italy,
vol. i. p. 82.)
The battle on the Trebia is alluded to by Lucan, and described by Silius Italicus: it is noticed also by all the epitomisers of Roman history; but none of these writers add anything to our knowledge of the details. (Lucan 2.46
; Sil. Ital. 4.484
; Corn. Nep. Hann. 4
; Eutrop. 3.9
; Oros. 4.14
; Flor. 2.6.12