Battle of The Trebia - Sources and Solutions

Sources and Solutions

The two main sources on the battle are the History of Rome by Livy (Book XXI) and Histories of Polybius (Book III). The two vary considerably in some of the geographical details and are ambiguous about some key points, especially whether the Romans were camped on the left bank or the right bank of the Trebbia and in which direction they crossed the river. Reconstruction of the disposition is the major scholarly concern regarding the battle. The sources all agree on the outcome.

Contending views stem from the confusion of real and hypothetical events, beginning with the supposed "union" of the two consular armies, which Sempronius had been ordered to effect. He was advancing "with all speed to join Publius." From the evidence, the supposed union amounted only to Sempronius having "many close conferences with Scipio, ascertaining the truth about what had occurred, and discussing the present situation with him."

Whether the union went any further is questionable. The two consuls maintained widely separated camps. Polybius assumes a union of troops would have been effected and Sempronius would be commanding four legions (he uses conditional language and not declarative statements). He explains how after the defeat Sempronius' army fell back on Placentia (Piacenza) but neglects totally to say what happened to the wounded Scipio and how he got to Placentia (Piacenza). Livy, on the other hand, although repeating Polybius' numbers, states that after the battle Scipio quietly marched his army into Placentia (Piacenza) and went on to Cremona so that there would not be two armies wintering in Placentia (Piacenza).

If Scipio's army was intact and quietly marched into Placentia (Piacenza), it is unlikely that either consul commanded any of the troops of the other nor did they assist one another in any way; in fact, there is no evidence that Sempronius informed Scipio he was going to attack. He is reported to have asked Scipio his advice on whether to attack and was strongly advised against it. There is no account at all of Scipio handing over any troops. If, as many authors suppose, Hannibal was trying to prevent a union, he seems singularly unaware of it. He made no move to stop Sempronius coming up from the east. The consuls themselves, however, each jealously guarded his own authority.

Starting with Polybius, some military writers throughout the centuries have assumed that because union was intended it was effected: this assumption leads to the problem known as "the Roman Camp." There were not one, but two, Scipio's in the hills on the left bank and Sempronius' in the plains on the right bank. Neglect of this duality leaves the writers free to select either (or neither) as "the Roman Camp;" consequently, it appears now on the left bank, now on the right; now in the hills and now on the plain.

Hannibal's perception of the non-union led him to the winning strategy. Provoking Tiberius to send his men wading through the chilled winter waters of the Trebbia during a precipitation of snow and rain, he attacked the Romans from ambush with his own rested, fed and warm men and killed 2/3 to 3/4 of them, driving the lucky ones back across the river to Placentia (Piacenza). The Romans, it is said, could scarcely lift their arms to defend themselves.