German M-Flak (3.7 cm Maschinenkanone Flak). From late 1915 M-Flak batteries defended balloons and important positions and installations
German M-Flak (3.7 cm Maschinenkanone Flak). From late 1915 M-Flak batteries defended balloons and important positions and installations. German flak units were part of the Air Service, whilst the majority of the Allied anti-aircraft units were part of the artillery. Sources: https://www.flickr.com/photos/drakegoodma