However, the concept of aerial artillery support is much older: military aviation, which appeared very early in the First World War, and its role was only observation, and subsequent guidance of artillery. The first highlight of this new weapon, whose contribution may have been decisive, took place on 3 September 1914, when squadron REP 15 observation airplanes, attached to the Sixth Army under Maunoury), realized that "the columns of Kluck spin to the south-east [... ]. There can be no question of a serious attack to Paris. "The hope was reborn in the French camp, reinforced by consistent reports of the British Expeditionary Force aircraft. In the hours following, airmen meticulously locate the different Imperial German Army corps. A gap formed between the First Army (Von Kluck) and Second Army (von Bülow). Reports were submitted to Joffre, who decides to take without further delay of this possibility. On 6 September 1914, the First Battle of the Marne began, and the German advance was cut short.