This article explores the changes and adaptation of warfare strategies in indigenous societies during the Spanish conquest, through a case study of Copiapo valley in northern Chile. Using ethnohistorical and archaeological data, it explores the experiences and actions of collective agents who transformed their warfare practices and social alliances in order to fight for their autonomy and survival. The Copiapo people transformed from a society characterized by low-scale intermittent warfare to one that employed an intensive mode of conflict and developed broader inter-ethnic alliances. Their relative success in this last stage eventually proved to be an effective bargaining tool to negotiate better conditions for their incorporation into the new colonial system.