After the fall of Sagonte in 219 BC, Hannibal turns his glance towards Italy. It quickly sees the opportunity to ally the Gauls. His ambassadors then make wonders in Cisalpina and come back to Spain with the insurance that the Gauls will help the Carthaginians. Hannibal thus crosses the Pyrenees. He covers the first Gauls he meets with a lot of presents for, being wary, they have taken their weapons. But they let the Carthaginian general pass through.

At the same time, Rome learns that the Insubrians and the Boians revolt against the transformation into colonies of their settlements of Placentia and Cremona. The Romans fail to take over the situation and send legions near Marseilles, a city remained faithful, in order to watch the progression of Hannibal and prevent him entering Italy by the coastal road. The Carthaginian then pays tribute to the Volsques, crosses the Rhone in August 218 and finally faces the Alps. Here as well, he allies the local Gallic tribes which he uses as guides to cross the mountain. It is the famous and appalling passage of the Alps where three quarters of the Punic army die - 75.000 men! But Hannibal is in the plain of Pô.

After the Punic victory of river Tessin (Ticino), the Gallic auxiliaries of the Roman army revolt and join Hannibal. But the Carthaginian understands that the Gauls tribes play a double game: the local tribe calls for help the consul P. Cornelius Scipion on the ground that the Carthaginians are plundering their lands. The Romans, seeing here a possibility of gaining the Gallic cause, disperse the Numidians raiders who are devastating the plain of Pô.

In fact, the Gauls do control this whole war game, so far that Gauls auxiliaries fight in both side during the battle of river Trebbia. The Cenomans, auxiliaries in the Roman army, will first fold towards the punic elephants and will escape and bring panic among the legions.

Hannibal continues his victorious walk. The following year, in 217 BC, at lake Trasimene battle, Hannibal has so little confidence in his Gallic auxiliaries that he places them at the center of his army and under special monitoring of his brother Magon. At Trasimene, whose outcome recalls the Romans Allia’s dark times, consul Flaminius is killed by a Gaul Insubrian who, before striking, tells him he avenges its fatherland of the Roman torturer. Following the Roman defeat, the Gauls join the Punics in mass.

Fabius Maximus is appointed dictator. It understands that the alliance between the Carthaginians and the Gauls is just circumstantial, and asks for patience. Hannibal, who lost half of his troops and does not have seige machines, does not besiege Rome but goes to the south of Italy. He seeks to turn over from Rome side the allied Italian cities.

But in the Eternal City, in 216 BC, the partisans of the attack take over the prudence of Cunctator Fabius Maximus, then depicted as cowardice. The Senate designates as consuls L. Aemilius Paullus and Gaius Terentius Varro. They cross the Apennines and face the front of Hannibal. It is the battle of Cannae.

Sextus Apollonius Scipio