This article studies the phenomenon of desertion from the Royal Army at the Chilean borders during the 17th Century. It proposes that desertion was caused by a number of factors such as the deficient funding structure of the royal military forces, the low quality of its soldiers, and certain practices such as the existence of collaborators and the lack of proper state surveillance at the borders and ports, which enabled soldiers to desert from their army. The study intends to reconstruct and analyze the reasons, modalities, routes and destinations of the deserters, as well as the military, social, and economic consequences of this process.