In this seminal work, Gustave Le Bon, the renowned psychologist and sociologist, delves into the profound psychological impact and societal dynamics observed during the European War of 1915. He masterfully applies his theories on crowd psychology and the irrational behavior of masses to analyze the collective mindset, propaganda, and emotional forces at play during this monumental conflict. Le Bon explores how the war reshaped individual and collective consciousness, offering timeless insights into human nature under extreme duress and the psychological underpinnings of large-scale historical events. This book remains a crucial study for understanding the psychology of war and the influence of crowds.