The Battle of the Trebia was the first major battle of the Second Punic War, fought between the Carthaginian forces of Hannibal and the Roman Republic in December of 218 BC.It was a significant Roman defeat with heavy losses.

In this battle Hannibal got the better of the Romans by exercising the careful and innovative planning for which he was famous. The impetuous and short-sighted opposing general, the consul Tiberius Sempronius Longus, allowed himself to be provoked into a frontal assault under physically difficult circumstances and failed to see that he was being led into a trap.

The battle took place in the flat country of the Province of Piacenza on the left bank of the Trebbia River, a shallow, braided stream, not far south from its confluence (from the south) with the Po river.

The Romans lead 42,000 men to battle, whereas Hannibal had approximately 30,000 men. Due to the Battle Carthagos' forces lost approximately 4500men, while their opponents at least 5 times as much.