 Complete the following phrase:  At the start of the war, in September 1914, De Scévola, serving as a second-class gunner, experimentally camouflaged a gun emplacement with a painted canvas screen. On 12 February 1915 General Joffre established the Section de Camouflage  at Amiens. By May 1915 the Section de Camouflage put up its first observation tree, an iron lookout post camouflaged with bark and other materials during the 