In captivity, de Gaulle read German newspapers (he had learned German at school and spent a summer vacation in Germany) and gave talks on his view of the course of the conflict to fellow prisoners. His patriotic fervour and confidence in victory earned him yet another nickname, "Le Connétable" ("The Constable"), the title of the medieval commander-in-chief of the French army. In Ingolstadt were also journalist Remy Roure, who would eventually become a political ally of de Gaulle, and Mikhail Tukhachevsky, a future commander of the Red Army. During his time as a POW, de Gaulle got to know well Tukhachevsky, whose theories about a fast-moving, mechanized army closely resembled his. While a prisoner of war, de Gaulle wrote his first book, "Discorde chez l'ennemi (The Enemy's House Divided)", analysing the issues and divisions within the German forces. The book was published in 1924.