Hannibal's Alpine Crossing

Hannibal, made commander of Carthaginian Spain in 221 BC at the age of 26, spent two years subduing the tribes south of the Ebro. The one city he left alone was Saguntum, an ally of Rome. In 219 BC he attacked it anyway. The siege lasted eight months, with famine inside the walls, and when the city fell Rome declared war — exactly the war Hannibal wanted. The hilltop castle of Sagunto, above the modern town north of Valencia, stands on the site of the ancient city.

Visitor guidance: The castle ruins and Roman theatre of Sagunto are open to visitors on the hill above the old town.

New Carthage, today's Cartagena, was the capital of Carthaginian Spain and Hannibal's base. In late spring 218 BC he marched out of it, by Polybius' count with ninety thousand infantry and about twelve thousand cavalry, crossed the Ebro and fought his way through the tribes of the Pyrenees, leaving garrisons and sending some men home as he went. The army that reached the Rhône was already much smaller. In Cartagena a stretch of the Punic city wall survives and can be visited.

Hannibal reached the Rhône where the stream was single, "at a distance of four days' march from the sea", and bought every canoe the locals had. A detachment crossed upstream on rafts to take the Gauls on the far bank in the rear. The elephants, which would not step into water, were led by two females onto huge rafts covered with earth to look like dry land, then towed across. Some panicked and plunged into the river; their riders drowned, but the elephants themselves swam ashore, breathing through their trunks.

Location precision: The crossing place is unknown; the pin marks the lower Rhône near Avignon, within the range historians propose.

Four days' march up the river from the crossing, Hannibal came to a district Polybius calls the Island, "thickly inhabited and exceedingly productive of corn", named because the Rhône and the Isara flow along its two sides. Most historians take the Isara to be the Isère, which would put the Island in the angle where it joins the Rhône, above modern Valence. Hannibal settled a quarrel between two brothers over the local kingship and was rewarded with food, clothing and new weapons for the climb ahead.

Location precision: The Island is identified only from Polybius' description; the pin marks the Rhône–Isère confluence.

The ascent took fifteen days of ambushes by mountain tribes, landslides and early snow. At the top, with his men exhausted and the snow beginning to lie thick, Hannibal pointed to the plains of the Po below, "giving the Alps the appearance of a citadel to the whole of Italy". On the way down, a landslip blocked the path, and the troops spent days cutting a new one. Which pass it was has been argued over for centuries: the Little St Bernard, Clapier, Montgenèvre, Mont Cenis and Traversette all have their champions.

Location precision: The pass is unknown; the pin marks the Col de la Traversette, one of several candidates.

Visitor guidance: The Traversette is a high mountain pass reached only on foot in summer; go with proper equipment and check conditions.

The whole march from New Carthage had taken five months. Hannibal came down into the territory of the Insubres with, as he later had carved on a column, twelve thousand African and eight thousand Iberian infantry and not more than six thousand cavalry. After resting his men, he turned on the Taurini, a tribe living at the foot of the Alps who refused his alliance, and took their chief town after a three-day siege. It is usually placed where Turin stands today.

Location precision: The Taurini's town is placed at Turin by tradition; the pin marks the city.

The consul Publius Cornelius Scipio hurried north to meet him, and in late November the two cavalry forces clashed on flat ground by the river Ticinus, west of modern Pavia. Hannibal's 6,000 African and Iberian horsemen routed Scipio's force; the consul himself was wounded and saved from death or capture only by his 16-year-old son — the Scipio who would one day defeat Hannibal. The Romans fell back across the Po.

Location precision: The battlefield's exact place isn't known; the pin marks the lower Ticino near Pavia.

On 22 or 23 December 218 BC, in midwinter, Hannibal sent his cavalry to provoke the consul Sempronius Longus before the Romans had eaten breakfast, drew them across the river Trebia near Placentia, today's Piacenza, and sprang an ambush hidden in a stream bed thick with brambles on their flank and rear. Most of the Roman force was killed or captured; only about 10,000 men fought their way out to the town. Hannibal stayed in Italy for fifteen years, winning again at Lake Trasimene and Cannae, but never took Rome.

Location precision: The battle was fought on the flood plain west of the lower Trebia; the pin marks the river.