International audienceIn this article we transpose the evolutionist approach, traditionally circumscribed to firms, to a territory analysis to understand its dynamics and perspectives of diversification. Concepts of constriction, trajectories and path dependency seem particularly relevant for studying the inertia of the Brest (France) area in terms of activities diversification. Marked by the defense industry, the country of Brest is struggling to realize the projects of diversification towards civil activities. We are advancing the idea that the defence industry, by its singularity, is at the origin of territorial footprints and cognitive, explaining to a large extent why local actors remain reluctant to any diversification project. The re...