Centurions in the Roman Legion: Computer Simulation and Complex Systems

The Centurion was a key figure of Roman warfare over a span of several centuries. However, their real role in battle is still a matter of discussion. Historical sources suggest that their impact in the efficiency of the Roman battle line was highly disproportionate to their individual actions, considering their low numbers. In the past decades a number of authors have proposed different descriptive models to explain their relevance, highlighting factors such as an improvement on unit cohesion or high levels of aggressiveness, which made them lead the charges against the enemy. However, the lack of a quantitative framework does not allow to compare and test these working hypotheses.This paper suggests an innovative methodological approach to explore the problem, based on computer simulation. An Agent-Based Model of roman legions is used as a virtual laboratory, where different hypotheses are tested under varying scenarios. Results suggest that the resilience of formations to combat stress increase exponentially if they contain just a small percentage of homogeneously distributed warriors with higher psychological resistance. Additionally, the model also shows how the lethality of the entire formation is reinforced when this selected group is located at the first line of the formation, even if individually they are not more aggressive or skilled than the average.The interpretation of the simulated patterns in terms of Roman warfare suggest that the multiple roles of the centurions observed in the sources were not caused by changes in tactics or values, but can be strictly explained by an increase in their experience and overall combat performance.