La Sirène, published by the Lyon branch of the Union Nationale pour la Défense Aérienne in Lyon, was one of several (usually short-lived) civil defence magazines to appear in the pre-war years. The trench-digging photograph is notable for the characteristic zig-zag pattern of the trenches, designed to resist the effects of blast, and for the unusual presence of a mechanical digger.
Courtesy Archives Municipales de Lyon, 1127/WP/09.
