Why do even the best armies in the world repeat fatal mistakes over and over again? Norman Dixon reveals the deep mechanisms of military failures — from the Napoleonic campaigns and the Crimean War to the battles of both world wars and the conflicts of the second half of the twentieth century. Uniqueness of the study: analyzes the key pitfalls of the mind and psychological factors of failure: biases, fears, excessive self-confidence of commanders. Reveals how the organizational culture of armies promotes disastrous decision-making by rewarding conformity instead of competence. It shows the universality of the problem using many examples that are understandable for any country or army. The book is relevant for today, because it explains how ignoring historical lessons costs millions of lives, or why a "three-day special operation" turns into war years. This is not only an analysis of past defeats, but also a tool for future victories — both for the military command and for leaders in politics, business and other fields. Norman Dixon is a former British officer and researcher in the field of Experimental Psychology. His book "Psychology of military incompetence", published in Ukrainian by the Nash format publishing house, became the subject of discussion not only among historians and military personnel, but also among a wide audience interested in politics, management and leadership. This study is devoted to the analysis of failures in military history, where the main factor of failures is not external circumstances, but the character traits of commanders. The author examines why armies in different eras went to obvious catastrophes, repeating the same mistakes, and what exactly in the psychology of managers prevented an adequate assessment of the situation. Dixon shows the consistency of the problem: from the Crimean War to the Second World War, revealing the mechanisms of thinking of those who made fatal decisions. The author raises the issue of responsibility and the nature of the authorities, emphasizing that the danger of authoritarianism and incompetence in the military leadership remains relevant today. This is a work not only about the past, but also about the present, because similar features can be recognized in the political environment of our time.