Hannibal's Crossing — HANNIBAL BARCA · 218 BC

In autumn 218 BC, at the start of the Second Punic War, Hannibal Barca led a Carthaginian army with war elephants over the Alps into Italy. Polybius counts 38,000 infantry, more than 8,000 cavalry and 37 elephants at the Rhône crossing, and 20,000 infantry and 6,000 cavalry on arrival in the Po valley — figures he says he took from an inscription Hannibal himself set up at Cape Lacinium. He says the Alpine crossing took fifteen days and cost nearly half the army. Polybius does not name the pass, and Livy says writers already disagreed about it in his day. Leading modern candidates include the Col de la Traversette (2,947 m), the Col du Clapier (2,477 m) and the Col de Montgenèvre (1,854 m); Mont Cenis and the Little St Bernard also have defenders.

Rome ruled the sea. So in 218 BC, with the Second Punic War barely begun, Hannibal Barca did the one thing no Roman planner had bothered to imagine: he took the war overland, marching out of Iberia and across the Rhône — where Polybius counts some 46,000 soldiers and 37 war elephants, with a long train of pack animals — and up into the Alps as autumn closed the passes.

The mountains fought back before the weather did. On the approach, Allobroges tribesmen fell on the strung-out column where the track ran along a precipice; in the panic, horses and pack animals went over the edge with their loads. Days later a second ambush — this one with boulders rolled from above — nearly finished the job. Hannibal spent the night with half his army at a bare rock (Polybius's leukopetron, often rendered 'white rock'), covering the defile while the horses and pack train crawled through.

Near the top the first snows of the season were already falling. Polybius says Hannibal gathered his dispirited army at the summit camp and showed them the plains of the Po below, pointing out where Rome itself lay. In Livy's version he tells them they are scaling the walls not just of Italy, but of Rome. They rested two days in the snow, then began the harder half — going down.

The descent was fresh snow over last winter's ice, and at its worst a landslide had carried the path away entirely. Polybius says Hannibal set his men — Numidians working in relays — to rebuild the path along the cliff: a day to get the horses and mules across, three for the elephants. Livy adds the famous detail that they cracked the rock by heating it with fire and dousing it with sour wine, and cut zigzags into the slope.

About 26,000 soldiers walked out into the Po valley — little more than half of the 46,000 Polybius counts at the Rhône crossing a month or so earlier. No source records an elephant lost in the mountains — Polybius says only that they came down half-starved — but nearly all of them died in the cold after the Trebia that winter. Before the year was out Hannibal had beaten Roman armies at the Ticinus and the Trebia, and the walls of Rome would spend fifteen years learning his name.

And the route? Nobody knows. Polybius and Livy left clues, not coordinates, and the argument is as old as Livy. The Col de la Traversette is brutal but has the only claimed physical trace — a churned, dung-rich mud layer dated to about 218 BC, which many historians don't accept as proof; the Col du Clapier has room for a summit camp and the view over the Po plain that Polybius describes; the Col de Montgenèvre is the low, easy road that later became Rome's main highway over the Alps. (Mont Cenis and the Little St Bernard have their champions too.) March all three and pick your side.

46,000 → ~26,000 SOLDIERS · 37 🐘