Two consuls face Hannibal
After the Ticinus, Scipio is wounded. Sempronius arrives with a second army. The Romans have substantial forces but must decide when to fight.
Military history
Why is a breakthrough in the Roman centre not enough to save the army?
In late 218 BCE, Hannibal draws the Romans across the Trebia. The cold and the crossing wear them down before battle. Punic cavalry drives off their flank guards, then Mago's detachment attacks the rear. Yet, according to Polybius, at least 10,000 Romans break through and reach Placentia.
An earlier success encourages Sempronius
A favourable skirmish strengthens his desire to fight. Polybius and Livy attribute to Hannibal the intention to exploit this disposition.
Preparation changes the conditions of the clash
On the day of battle, Numidian cavalry draws the Romans out of camp. They cross without having eaten, while Hannibal’s men prepare and warm themselves.
An ambush in discreet cover
Mago waits with a mixed detachment in a brush-lined watercourse. The exact locations of the camps, crossing, and hiding place remain disputed.
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Chronological dossier
TicinusHow did the Numidians tip a cavalry battle that had remained undecided?Lake TrasimeneFog, hills and lake compress a Roman march into a prepared trap.CannaeHannibal envelops the Roman legions: the centre falls back, the wings are attacked, and the cavalry returns. A major victory that does not end the war.New CarthageHow do you open a fortified city by forcing its defenders to look elsewhere?MetaurusHow does Nero turn a wing blocked by the terrain into an outflanking force?IlipaHow can you beat an army’s wings without engaging its best troops in the centre?ZamaWhy do Hannibal’s veterans give way after resisting the Roman infantry?
Military history
Sources
Digitised primary sourcePolybe, Histoires, livre III
III.69–74, rubriques « Hannibal Prepares An Ambush », « Preparations for Battle », « The Battle of the Trebia » et « The Romans Retreat to Placentia »
Preliminary skirmish, motives attributed to the commanders, Mago's detachment, army preparations, reported strengths, sequence of centre and wings, survivors, and retreat.
View ↗Digitised primary sourceTite-Live, Histoire romaine, livre XXI
XXI.52–57, surtout 52–54 pour la décision et la cache, 55–57 pour la bataille et la retraite
Parallel account of the skirmish, advice to delay, preparation of the ambush, crossing, fighting, losses, and Roman escapes.
View ↗Specialist military-historiography articleMartin Samuels, « The Reality of Cannae »
Militärgeschichtliche Mitteilungen 47.1 (1990), pp. 20–21, section « Battle of the River Trebia »
Reconstruction of orders of magnitude and deployment, role of light troops and cavalry, and Mago's rear attack; these calculations remain a modern interpretation.
View ↗Specialist monograph on military topographyJohannes Kromayer et Georg Veith, Antike Schlachtfelder, Band 3
Berlin, 1912, pp. 47–103; surtout 48–57 « Die Kontroverse », 57–78 opérations et champ de bataille, 94–98 effectifs, 99–103 Polybe et Tite-Live
State of the topographical controversy, discussion of operations and battlefield, critical comparison of the narratives, and strength tables.
View ↗Research article in specialist historiographyTenney Frank, « Placentia and the Battle of the Trebia »
Journal of Roman Studies 9 (1919), pp. 202–207, notice et extrait sur la localisation disputée et la fiabilité comparée de Polybe et Tite-Live
Historiographical boundary on locating the engagement: the controversy concerns not merely cartographic curiosity, but also interpretation of the sources.
View ↗Specialist academic workJohn F. Lazenby, « Trebia », Oxford Classical Dictionary
Extrait public de l’entrée : 36 000 fantassins et 4 000 cavaliers romains conduits sur la rive gauche, environ 29 000 fantassins et 11 000 cavaliers chez Hannibal
Modern check of the battlefield bank, orders of magnitude, and Punic cavalry superiority; precise local placement remains bounded by Frank and Kromayer.
View ↗Specialist institutional encyclopaediaEnciclopedia Italiana, « Trebbia »
Entrée « La battaglia della Trebbia », §§ sur le contexte, la date, le dispositif, le combat, les pertes et les conséquences
Institutional synthesis of the sequence, orders of magnitude, general river topography, breakthrough towards Placentia, and limits of casualty figures.
View ↗Institutional map (USMA)Department of History, United States Military Academy, « Map of the Battle of Trebia »
Carte créditée au Department of History, United States Military Academy, publiée le 26 avril 2012; fiche « Map of the Battle of Trebia »
Independent relational check of the river–camps–movements axis; the map is an educational reference, not proof of precise local coordinates.
View ↗Local institutional sourceVisit Piacenza, « Trebbia river: scene of many battles »
Notice touristique officielle sur la bataille de 218 av. J.-C., propositions de campements et retraite vers Plaisance
Local evidence of location hypotheses around Piacenza; used only to flag those proposals, without turning a local tradition into certainty.
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