In the course of the general Italian mobilization during World War I, he was drafted again by the army in October 1915. Together with his later friend Pietro Ghiglione, a mountain climber and writer, he served in the 3rd Alpini Regiment. Concerning to his advanced academic studies, he was made Sottotenente, became Tenente in 1916 and Capitano in 1917. During his services he was technical director of military ski training. He gave his first course at the Little St Bernard Pass,the second in the Champorcher Valley, and further ones in several alpine areas apart the conflict areas. All in all he trained about 3,000 White Warriors from the Adamello of 26 skiing units of 13 battalions until 1917, the year when the 3rd Alpini Regiment got the name affix Courmayeur