This paper analyses the Spanish Civil War combatants’ private diaries as an alternative and/or complementary source to more conventional ones for the study of the conflict. The study mainly focuses on the lifespan of the sub-genre ’personal diary’ as an historical text, highlighting the reasons for its relevance as compared to other individual documents, the reasons for its onset, the importance of daily writing habits for the author, the eventual writing abandonment, later use of the document, and the main topics reflected by the combatants. The paper focuses on the analysis of 30 personal diaries, a substantial amount that allows for considering those texts as essential historiography sources. All this contributes to a closer, more tangible and more attractive interpretation and study of the conflict than the conventional ones do.