Grenzschlachten
Achard enlisted into the French Army on 7 August 1913. After passing the entrance examination he entered the military academy at Saint-Cyr as an officer cadet on 6 September, and was commissioned as a "sous-lieutenant" on 6 November. On 12 August 1914, soon after the outbreak of the war, he was posted to the 9th Hussar Regiment, which was engaged in the Battle of the Frontiers and the subsequent Race to the Sea in late 1914. On 17 March 1915 Achard was transferred to Army's aviation branch – the "Aéronautique Militaire" – training at Le Bourget to become an observer.