Where did Hannibal cross the Alps (Part 1) Col de la Traversette

It  was a year ago this week that newspapers around the world reported that the 2,200 year old mystery as to where Hannibal had crossed over the Alps may have been solved. The newspapers printed the results of an investigation by Professor Bill Mahaney of Toronto University and his team into samples of soil taken from the Col de la Traversette in France, which they claimed proved that Hannibal has crossed over this pass in 218 BC. Scientific studies are published in scientific journals every day and they very rarely make headlines in the world’s media. But that was not the case with Professor Mahaney’s investigation and the Guardian, Telegraph and many other newspapers reported on it. In Ireland, the Irish Times, published an article saying that the 2,000 year argument over Hannibal’s route through the Alps had been “settled” due to evidence of “poo, lots and lots of poo”. The soil samples that Professor Mahaney and his team analysed showed the presence of considerable amounts of fecal matter from horses and other animals dating from around 200 BC. The results certainly prove that there was a large herd of animals, possibly from an army, at one time on the Col de la Traversette over 2,000 years ago. But as to whether the results prove that Hannibal crossed the Alps via the Col de la Traversette., as claimed by Professor Mahaney, is another question.

Location of the Col de la Traversette and other Alpine passes Hannibal may have used. Source: Wikipedia

Just where Hannibal crossed the Alps with his army of 30,000 men, 5,000 horses and 37 elephants has perplexped scholars for over 2,000 years. Some historians insist he used the safest and arguably the easiest route to Italy across the Col du Petit Saint Bernard. Others insist that he didn’t march as far north and instead crossed over either the Col du Clapier or Mont Cenis. But many other historians, including Professor Mahaney, believe Hannibal may have used the shortest and most direct route to Italy across the Col de la Traversette. In order to prove that Hannibal used this pass, Professor Mahaney organised a team of geologists and biochemists and they undertook a number of field expeditions to the Col de la Traversette between 2011-2015 to take soil samples from a small area of pasture near the summit.

Scientists retrieving soil samples from the Col de la Traversette. Source : Irishnews.com

In April 2016, Canadian professor, Bill Mahaney, announced that he had discovered evidence that a huge herd of horses had passed over the Col de la Traversette 2,200 years ago. Samples of sediment from a lake near the pass were tested by Dr. Chris Allen at Queen’s University in Belfast and by Dr. Brian Kelleher at Dublin City University who concluded that they contained bacteria often found in horse manure. The samples were then carbon dated to around 200 BC, which coincided with the time that Hannibal had marched from Spain all the way to Italy to attack Rome.

Carthaginian and Roman territory in the 3rd Century BC. Source : Slideplayer.com

You can see from the map above that Carthage controlled more territory than Rome around 220 BC. Rome had defeated Carthage in the First Punic war around 240 BC and as a result, gained control of Sicily. To compensate for losing Sicily, the Carthaginians invaded Spain from their base at modern day Cartagena. During this campaign, Hannibal’s father was killed and Hannibal took control of the Carthagian forces in Spain. It is well known that to gain revenge for losing the first Punic war, Hannibal decided to assemble an army and attack Rome by crossing into Italy via the Alps. What is not so well known about Hannibal’s mission is that he only decided to attack Rome via the Alps after receiving a visit from Gallic envoys, who had traveled all the way from northern Italy to southern Spain to meet him. The Insubre and Boii tribes had recently been defeated by the Roman army and their land in northern Italy along the Po valley was confiscated. So they were hoping that Hannibal would help them to regain control of their land and they promised Hannibal their full support if he would assemble an army to attack Rome.

Hannibal’s army on the march. Source: Wikipedia

Hannibal set out from Hispania in March 218 BC with an army of perhaps 50,000 men, 5,000 horses and 37 war elephants. His march was first recorded by the Greek historian Polybius around about 140BC and then also by Livy  around about 50BC. About 2 months after crossing the Pyrenees, Hannibal arrived at the Rhone river. Most historians accept that he crossed the river near the modern day city of Orange. Where he went next, however, has been subject of a long but inconclusive debate. In the years since, there have been over 1,000 books published about Hannibal and no two books include exactly the same route.

One possible route Hannibal took through the Alps. Source: Wikipedia.fr

Where Hannibal went after crossing the Rhone has remained a mystery to this day. Polybius, the Greek historian, tells us that he crossed the Rhone at a place about four days’ march from the sea, and that he then turned east towards the Alps at a place called ‘the Island’, at the confluence of the Rhone and the River Iskaras, a further four days’ march up the Rhone. Some historians believe the river Iskaras to be the modern day River Drome and Hannibal then made his way up the Durance valley towards the Alps as shown in the map above. This route was championed by Gavin de Beer in the 50’s and is also the route favored by Professor Mahaney. Between 2011 and 2015, the Canadian professor organised a team to take core samples of soil from the vicinity of the Col de la Traversette to see if they could find any evidence that a large army had crossed over this pass.

Typical core samples from various locations around the world. Source: Wikipedia

The above photos show typical core samples from various sites around the world. It is fascinating to see what evidence scientists can extract from examining pollen and other plant seeds found in a core. In a similar way to studying rings in a tree, they can work out the climate from 1,000’s of years ago. For example, the core sample on the left above was obtained from Chesapeake Bay in north eastern USA. The core is about 20 feet long and goes back 18,000 years to the end of the Ice Age in north eastern USA. By examining the pollen in the sample, scientists can identify the Little Ice Age period between 1450 and 1850 as well the Medieval Warming period between 900 -1200.

Photo of the trench and core sample analysis from the Col de la Traversette. Source : onlinelibrary.wiley.com

On the 27th of July 2016, Professor Mahaney’s article in the Archaeometry journal was published online on the Wiley Open Access website and released under a Creative Commons licence. You can clearly see the churned up animal manure layer below the dashed line in the image of the trench above. The MAD (mass animal deposition) layer was determined by studying various samples for the Clostridium bacteria and is located between 35 and 50 cm below the surface. In all, 6 samples were carbon dated to determine their age and the top sample at the boundary between the fibrist and hemist layers was dated to 1130 years BP (Before Present-day). In the churned up layer, a range of dates between 2070 BP and 3540 BP were discovered which Professor Mahaney explained as a result of deeper sediment being churned up by the hooves of Hannibal’s horses and mixed with younger sediment. But there is a fatal flaw in this argument as you one of the dates in the churned up MAD layer is from 2070 BP + or – 31 years. So this sample dates from between 23 to 85 BC or at least 140 years after Hannibal crossed over the Alps. If the churned up MAD layer was caused by Hannibal you would not expect to find a sample date from after his crossing, only dates from before 218 BC. Instead, the churned up layer could have been caused by a different army around the time of Christ. But it is more likely that the churned up layer was caused by the thousands of medieval mules transporting heavy loads of salt up and over the mountain up until the tunnel under the Col de la Traversette was opened in 1480.

Col de la Traversette tunnel also known as the Monte Viso tunnel. Source: Envie de Queryas.com

While the Col de la Traversette was rarely used 2,000 years ago in Roman times, it was a major throughfare for the local people in medieval times, roughly a 1,000 years ago. Salt was very important in times gone by to preserve meat and other foods and there was a lucrative trade in salt from the Mediterranean across the Alps to the Po valley. The most direct route from the salt farms near Arles to the Po valley was via the Col de la Traversette. This trade route was so popular that in 1480, a 75m long tunnel was dug under the Col de la Traversette at around 2,800m in altitude. The tunnel took 3 years to dig most likely using just rudimentary tools and maybe gunpowder. It was an incredible feat of engineering and is arguably the first international tunnel built anywhere in the world. There must have been an incredible volume of salt being transported up the Col de la Traversette to make it worth the salt traders time to dig such a tunnel. So up until 1480 when the tunnel opened, there must have been thousands of mules with loads of salt who crossed over the Col de la Traversette. Many of these mules would have stopped to drink at the lake near the summit where Bill Mahaney and his team extracted 2 cores from the sediment. So you would expect these cores would also have a layer mule fecal deposition layer from around a 1,000 years ago as well as a horse fecal deposition layer from 2,200 years ago. However, there is no evidence of 2 separate layers from the core samples published by Professor Bill Mahaney.

An artist’s depiction of Hannibal Crossing the Alps. Source: Wikipedia

It is interesting to compare the reports of the Col de la Traversette core samples in the English and American press with that of the French press. In Ireland, the Irish Times, the so-called “paper of record” published an article saying that the 2,000 year argument over Hannibal’s route through the Alps had been “settled” due to evidence of “poo, lots and lots of poo”. A thin slice in 2 core samples a few feet apart is not even evidence of lots and lots of poo let alone proof that this is where Hannibal crossed the Alps. To be fair, most of the other reports in the English speaking press played down the hype and simply reported that the carbon dating may have proved that Hannibal may have passed over the Col de la Traversette 2,200 years ago. But, in my opinion, the conclusions of Professor Mahaney and his team are as threadbare as the clothes the Carthaginian soldiers are wearing in the above painting. Interestingly, in the French press, the findings of Professor Mahaney were dismissed out of hand. Geoffrey Galbert wrote that at least 5 armies crossed over the Alps between 250 BC and 100 BC and any one of them could have left the fecal layer discovered in the core sample. Most historians were also skeptical of Professor Mahaney’s conclusions. Tom Holland, writing in The Times said that the latest evidence is “literally a pile of manure”. Mary Harrsch from Ancient Times was also dismissive but wondered if equine DNA could be extracted from the churned up layer to determine the breed of horses to see if they may have been from the Numidian cavalry. However, disappointingly, there is no mention of DNA in the journal  or of any attempt to determine the climate from the pollen in the core.

Possible routes Hannibal may have used to cross the Alps. Source : Dublin City University

The above map was published on the Dublin City University website to co-incide with the publication of Professor Mahaney’s investigation and shows in black (towards the bottom of the map) the Gavin de Beer route the Professor Mahaney believes Hannibal used to cross the Alps. But the map also shows the location of the Allobroges and Insubres tribes. We know from both Polybius and Livy that Hannibal crossed Allobrogues territory before meeting up with the Insubres and then attacking the Taurini. But the Gavin de Beer route goes nowhere near the Allobrogues or Insubres territory and that is why a lot of historians have dismissed Professor Mahaney’s findings. The map above is not very clear but it does show in white the Col du Clapier-Mont Cenis route which I will investigate in Part 2 of this 3 part analysis of where Hannibal crossed the Alps. What is not shown on this map is the Petit Saint Bernard route which connects the Allobrogues and Insubres territory and which was the main throughfare for the Gallic tribes 2,200 years ago. This is the route that I believe Hannibal took to cross the Alps and I will explain why in Part 3.

Possible routes Hannibal may have used to cross over the Alps in 218 BC. Source: Author, Datawrapper

Update August 2020 : This article is just one of a total of eight articles I have wrote so far examining the mountain passes Hannibal may have used to cross over the Alps.

Article 1 (published 2017) – Col de la Traversette

Article 2 (published 2017) – Col du Clapier or the nearby Mont Cenis

Article 3 (published 2017) – Col du Petit Saint Bernard

Article 4 (published 2018) – Col de la Traversette (updated) – includes a review of the Channel 4 documentary Hannibal’s Elephant Army : The New Evidence.

Article 5 (published 2018) – Col du Montgenevre

Article 6 (published 2018) – Col du Petit Saint Bernard (updated) – added extra evidence and also some photos taken during a road-trip in August 2017.

Article 7 (published 2020) – Col de Couz – where French archeologist Aime Bocquet believed Hannibal was ambushed on his first day in the Alps.

Article 8 (published 2020) – Col du Chat – where American historian Theodore Dodge believed Hannibal was ambushed on his first day in the Alps.