A happy time for these three Wehrmacht soldiers. Looking from the sleeve patch, at least one of them (at right) is a Nachrichtentruppe member. The Nachrichtentruppe, in the sense of signal troops, were an arm of service in the army of the German Wehrmacht and Waffen SS, whose role was to establish and operate military communications, especially using telephone and radio networks. By order of the Oberkommando der Wehrmacht dated 14 Oct 1942, it was part of the combat arms of the German Wehrmacht and Waffen SS until 1945. The colour allocated by the Wehrmacht and Waffen SS in 1935 to their signal corps was lemon yellow. By contrast, the corps colour of the air force signal troops of the Luftwaffe was brown. The precursor of the German Signal Corps was the Telegraph Corps formed in 1899 as a separate arm of service. Telegraph battalions, fortress and army signal units were not combined into the signal corps, the Nachrichtentruppe, until 1917, during the First World War. In addition to radio and telephone communications, the newly developed teleprinters, carrier pigeons and heliographs were used for messaging. During the First World War, radio telegraphy took on increasing importance. For example, in 1915 teleprinters were first used by the air force, for artillery observation. In 1916, the first signallers equipped with mobile radios were operating on the front line.