Hannibal's crossing of the Alps

Did You Know?

• After the First Punic War, Hamilcar Barca sought to remedy Carthage's losses in Sicily and was embittered by the loss of Sardinia.
• The Romans had been at war with the Padane Gauls off and on for more than a century, and the Boii waged war from 238 to 236 BC.
• Hannibal sent embassies to the Gallic tribes in the Po Valley in 220 BC, offering money, food, and guides.

March through the Pyrenees

After the winter following the siege of Saguntum, Hannibal dismissed his troops in Cartagena to boost morale for the difficult campaign ahead. He left his brother Hasdrubal in charge of Carthaginian Iberia and its defense against Rome, and swapped Iberian and African troops between the two regions to reduce desertion and ensure loyalty. Hannibal also left ships with his brother. Foreseeing that Catalonia could serve as a Roman bridgehead, he decided to conquer the region swiftly, dividing his army into three columns to subdue it simultaneously.

After receiving route information from scouts and messages from Celtic tribes near the Alps, he set out with 90,000 heavy infantry and 12,000 cavalry. From the Ebro to the Pyrenees, the Carthaginians faced four tribes: the Illergetes, the Bargusii, the Aeronosii, and the Andosini. Hannibal took several unspecified cities, and Polybius reports severe losses. After reducing the area, he left his general Hanno in command, particularly over the Bargusii, whom he distrusted due to their Roman affiliation. Hasdrubal was left with 10,000 infantry and 1,000 cavalry.

Crossing the Rhône

Modern historians agree on the location where Hannibal encamped on the western bank of the Rhône and view the river crossing as clearly conceived and crisply executed. While Rome was idle, the Massaliots, Roman allies, roused tribes on the eastern bank against the Carthaginians. Upon learning of Hannibal's proximity to Massalia, the consul abandoned his Iberian expedition and sent 300 cavalry up the left bank to locate the Carthaginian army. Hannibal, aware of a Roman consular army of 22,000 foot and 2,000 horse, used the Celts' hatred of Rome to secure boats and canoes for crossing, a process that took two days.

On the eastern bank, the Cavares tribe had fortified a camp to attack the Carthaginians as they crossed. Hannibal, likely aware of Alexander the Great's crossing of the Hydaspes, employed a similar strategy. He ordered his lieutenant Hanno, son of Bomilcar, to make a northern circuit, cross the Rhône at a suitable location, and then march south to take the barbarian army in flank while Hannibal crossed.

From the Rhône to the Alps

Hannibal needed to reach the Alps quickly to beat winter and prevent the Romans from raising another army. He sent 500 Numidian cavalry down the eastern bank to gather intelligence. They encountered 300 Roman scouts, resulting in 240 Numidian and 140 Roman casualties. The Numidians were followed back to the Carthaginian camp, which was nearly assembled except for the elephants.

The Roman scouts raced to alert the consul, who dispatched his army upriver by boat but arrived too late. Facing winter and hostile tribes, the consul returned to Italy to await Hannibal's descent from the Alps, but ordered his brother Gnaeus Scipio to take most of the army to Spain to attack Hannibal's communications. The Romans were not accustomed to forcing battle by cutting off supply lines and were negligent in march order. After crossing the Rhône, Hannibal introduced his army to Magilus and other Gallic chiefs of the Po Valley to inspire confidence.

Magilus, speaking through an interpreter, spoke of Padane Gallic support for the Carthaginians. Hannibal then addressed his officers, and the troops' enthusiasm was uplifted.

Ascent of the Alps

Hannibal's actual route through the Alps is uncertain, and the valleys and passes he crossed are contested by historians. The identification of the pass—the highest point of his route—determines which path his army followed. Proposed passes include the Little St Bernard Pass, Col de Clapier, Col de la Traversette, Col de Montgenèvre, and the pass near Mont Cenis. Theodore Ayrault Dodge argued for the Little St Bernard Pass, while John Francis Lazenby concluded Col de Clapier.

W. C. Mahaney has argued for Col de la Traversette, supported by biostratigraphic data: analysis of peat bogs showed heavy disturbance by thousands of animals and humans, with traces of Clostridia bacteria from horse and mule digestive tracts. Radiocarbon dating secured a date of 2168 BP, or about 218 BC. Mahaney et al. concluded this strongly supports Col de la Traversette, as argued by Gavin de Beer in 1974. De Beer, John Lazenby, and Jakob Seibert were the only interpreters to visit all Alpine high passes and present a view; De Beer and Seibert selected Col de la Traversette.