Using GIS and Geophysics to Examine Caesar’s Campaign against the Helvetii in 58 BC
Channel: Recording Archaeology
Date: 2015-05-21

Abstract In the first chapter of “Comentarii de Bello Gallico” Julius Caesar recounts his campaign against the Helvetii in 58 BC. He asserts that the forces arrayed against him included 92,000 warriors amongst a mobilised mass of about 368,000 Gauls. This far outnumbered his six legions of ~30,000 men. Other interpretations of the campaign calculate a much smaller Gaulish contingent; with as few as 16,000 warriors. But what were the actual numbers? The generally accepted view is that Caesar inflated them for political gain. Caesar also explains the Helvetian incursion as arising from the pressures of Germanic tribes north of the Rhine, and the constriction of the Alps and Jura on their available resources. Can we perhaps shed some light on these assertions? Were the pressures on the Helvetii due to stress on the regional carrying capacity? Or can we perceive other economic advantages behind their migration? The aim of this paper is to examine a few of these issues using new techniques for modelling human energetics and dynamic mobility. This on-going three part project is aimed at developing: 1) a large-scale GIS simulation of the economic situation across all of the Helvetian territory as it existed just prior to the war, addressing the mechanisms of energy capture, exchange, storage, and loss in the context of the various population estimates; 2) a medium-scale model for kinetic energy expenditure by both groups specifically along the Rhône defences, and; 3) remotely sensing archaeological signatures in the small scale area known as Le Mandement (located just outside of Geneva, Switzerland). The specific landscape visualisations focus on the situation as it existed prior to the war across all of the Helvetian territory, and locally in the region of the Rhône between Lac Leman and le Pas d’Ecluse. The former as an expression of potential energy sources (e.g. agricultural and pastoral productivity, plus wild and semi-domesticated resources), as well as systems of energy exchange, transport, storage, and loss. The latter is examined as a model for kinetic energy expenditure (e.g. the building and maintenance of the wall to dramatically increase the “friction” costs of the invasion), and the tenuous nature of long-range energy supply (i.e. the Roman supply lines). Ultimately these examples provide ways of illustrating patterns of past human behaviour and movements that can be spatially quantified but are perhaps difficult to identify archaeologically. They can also be seen as insights into the cognitive processes employed by past people such as Julius Caesar, who did, in fact, keep track of, evaluate, and forecast the energy costs of politics, battles, and their future payoffs. Our goal in this presentation is to present the results of the large scale GIS landscape modelling, some preliminary geophysics findings and issues on both the medium and small scales, and to take a look forward to our proposed next steps in the process.

Authors: Thomas G. Whitley, Geoff Avern, Christine Markussen, Katie Simon