Alonso González de Nájera's Desengaño y reparo de la guerra del Reino de Chile (1614), is a capital text to understand the conquest of Chile in the early seventeenth century. This paper summarizes the most important challenges that the editor has faced in the ecdotic field (from tracing the manuscript and the printed editions to transcription and binding of the final text) and the hermeneutic field, taking account of the extensive passages dedicated by the author to describe geography, flora and fauna of Chile, the Mapuche people and especially the reasons for the poor results that the Spanish army had in the Araucania.