In August 1914, at the beginning of the Great War, he returned to Egypt and served as an officer in the Imperial and Royal Wehrmacht of Austria-Hungary. With the beginning of the war between Italy and Austria-Hungary, he was sent to the front on the Isonzo River. He fell ill with malaria, but he was not sent away from the front until he suffered a severe shock from a heavy Italian artillery attack near Gorizia. After eight months in the hospital, he moved at the end of 1916 to the Swiss resort town of Davos for further recuperation and rehabilitation. While there he wrote six chapters of his book Men in War, which deals with the Great War at the River Isonzo front. The book was a great success and translated into 19 languages. However, every country involved in the war banned it, and the army supreme command demoted Latzko.