Friday, August 8, 2014

GIS model tests Caesar’s accounts of the Gallic Wars

According to Caesar’s account of his Gallic Wars (58-51 BCE) over 250,000 Helvetii abandoned their territory in what is now northern Switzerland and attempted to relocate to Gaul in 58 BCE (Commentarii de Bello Gallico, Book 1, chapter 28).

Was Caesar exaggerating the size of the migrating population in order to increase the importance of his final victory over the Helvetii, and did encroaching famine really play a part in the decision of these people to move?

The Helvetii

Previously, the Celtic Helvetii under pressure from Alamanni in the 2nd century BCE, had migrated from southern Germany into what is now northern Switzerland. In March 58 BCE however, under the leadership of Orgetorix they moved en masse to western Gaul. Julius Caesar, at the start of a campaign to subdue and annexe Gaul, refused them entry and followed them along the banks of the River Saone, where he eventually defeated them near Bibracte. The remains of the Helvetian force which included all the non-combatant men, women and children as well as their warriors,  returned to Switzerland, and of the supposed 250,000 only 110,ooo were said to have survived.

Later, under Augustus, their territory formed part of Gallia Belgica and the capital at Aventicum (Avenches) became a Roman colony, with the baths at Aquae Helveticae (Baden, Switz.) becoming a well known site for visitors.

In a twist of fate, the Helvetii end up manning the Roman frontier forts against the Alamanni until at last they succombed to their ancient enemy by the mid-5th century. The name Helvetia or Confederatio Helvetica survives as an official name of Switzerland.

Modelling large scale economic systems

To try to answer the question of why the Helvetii migrated en masse, University of Western Australia (UWA) archaeologist Tom Whitley is developing a geographic information system (GIS) model to examine a large scale economic system of their lands, focussing on subsistence farming. His team will attempt to analyse both wild and agricultural sources of potential energy available in the local environment. The model tests Caesar’s assertions that they numbered quarter of a million against the amount of calories that would have been available to the people if they had completely populated the territory.

Professor Whitley explains, “Does that in fact reflect what he was saying, that there was a stress on the amount of energy that is available versus how many people are there to use it?” and he continues, “Or does it look like he’s exaggerating his numbers to make it look like he defeated more people than actually he did?”

The team are using the historical account, ecological and archaeological data which will allow them to construct detailed models of a complex economic system as they admit that it is difficult to reconstruct what was going on from the archaeological data alone as it is a very fragmentary record.

With computer simulation the researchers can quickly model a variety of different stress effects and view the potential results.

Roman military infrastructure

A secondary part of the study aims to find specific archaeological signatures for the war, such as Roman riverfront fortifications.

“Some of the GIS modelling is intended to say where it is likely that the Romans would have been building these structures,” he explains.

“Can we simulate what that past environment looked like where people were likely to have crossed and … go to those locations and see if we can find them?”

Using this form of predictive terrain modelling, the team are also testing the effectiveness of ground-penetrating radar, magnetometry matched with aerial photogrammetry, to see if the potentially massive Helvetian encampments can be identified on what are now vineyards and small farms.

Vineyards contain wire and metal posts, making magnetometry impractical, and radar can only be used in strips between the vines, no one technique can be used in isolation. The results will be released next year.

Past Horions. 2014. “GIS model tests Caesar’s accounts of the Gallic Wars”. Past Horions. Posted: June 29, 2014. Available online:

No comments: