Nobody knows which pass Hannibal used to cross the Alps
Hannibal's march over the Alps into Italy in 218 BC is among the most celebrated feats in ancient warfare, yet its route remains a mystery. There is no archaeological trace, and the two ancient accounts give only a scattering of place names. French historians even coined a word, Hannibalism, for the hopeless hunt.
The main sources are Polybius, born about 20 years after the crossing, and Livy, born about 160 years after it. Polybius offers just three place names, an Island, Skaras and the Allobroges, while Livy names more tribes and places; modern theories all depend on matching these to the landscape. In his 2022 book Hannibal in the Alps, the Dutch historian Jona Lendering argued that the accounts are too thin and contradictory to settle the question at all.
The motive runs back a generation. After losing the First Punic War, Carthage paid Rome tribute and lost Sicily, then Sardinia, which embittered Hamilcar Barca, whose surname means lightning. From 238 BC he spent nine years conquering south-eastern Iberia as a base for revenge and a replacement source of wealth. He was killed in 228 BC, with Hannibal present; his son-in-law Hasdrubal the Handsome took over, and Rome drew a line at the Ebro. When Hasdrubal was assassinated in 221 BC, the army elected Hamilcar's son Hannibal, then 26, as commander.
Hannibal subdued Iberia south of the Ebro except for Saguntum, a city under Roman protection, and tried to provoke the Saguntines into starting the war so he would not have to break the peace himself. His intelligence was excellent, with Gallic spies reportedly reaching into the Senate's inner circle. He also knew Rome's grip on the Po valley Gauls was raw: the Boii and Insubres had fought and lost in the 220s BC and had seen their land handed to Roman colonists.
The mountains were chosen deliberately. Marching overland let him bypass Rome's garrisons and its command of the sea. From 220 BC his envoys offered the Po Gauls money and asked for food and guides, because he knew the Italian descent was steeper than the climb and he did not want to stumble into battle with an exhausted army. Polybius credited him with consummate judgement in securing local guides who shared his hopes.
Source: Hannibal's crossing of the Alps
