His army of more than 30,000 infantry, 5,000 cavalry, and 37 battle elephants from Morocco marched through the autumn from Spain, which he had taken. When they reached the Alps some of Hannibal’s soldiers died of exposure in the bitter cold, while others fell to their death; only about half of them reached northern Italy.
Argument still rages over where the Alpine crossing took place. While there is general agreement that Hannibal moved up the Rhône from Avignon almost to Valence, from there onwards every valley and pass has had a case made for it being the route across the mountains into the plain of the Po near Turin. In 1959 an elephant called Jumbo was taken over the Col du Clapier by the British Alpine Hannibal Expedition to prove the route’s feasibility. This adventure was immortalised in John Hoyte’s book, Trunk Road for Hannibal. In 1988 the cricketer Ian Botham did the same thing, but with three elephants, in aid of leukaemia charities.
From the Col du Mont Cenis in the north to the Col Agnel 35 miles (60km) almost due south of it three approach routes have been argued for. In the most recent study, Dr William Mahaney, a geomorphologist, and his colleagues have looked at the evidence from Classical sources.
“As documented by Polybius and Livy in the ancient literature, Hannibal’s army was blocked by a two-tier rockfall on the lee side of the Alps, a rubble sheet of considerable volume,” they note in the journal Archaeometry. “The only such two-tier landform lies below the Col de la Traversette, 2,600 metres above sea level, a rubble sheet with sufficient volume to block the Carthaginian army.
“The character of the rockfall can best be seen from the sides or below, where a thin cover mass lies atop a much larger and more substantial rubble mass,” they say. “The trail cuts across a steep bedrock slope laced with a two-tier combination of rockfall and slide, just as Polybius described more than 2,150 years ago.” The trail has been shored up with ballast one to two metres thick, and Dr Mahaney’s team believes that artefact evidence may survive: “The three-day struggle to forge a path through the rockfall must surely have resulted in the abandonment or loss of implements used by Hannibal’s troops to prepare a path with sufficient ballast to support the passage of the baggage train, horses and elephants.”