The Junkers J.1, which flew for the first time early in 1917 and became operational at the beginning of 1918, was an all-metal biplane designed for close support and tactical reconnaissance. Its crew, whose main task was to fly at low level over enemy lines and report troop and vehicle movements via a radio link, was protected by a considerable weight of armour. This made the J.1 heavy, earning it the nickname Mobelwagen (Furniture Van). Manufacture was shared between the Junkers and Fokker factories, which produced a total of 227 aircraft between them. Instead of radio equipment, early J.1s carried two downward-firing Parabellum machine guns, but these were deleted because of problems with accurate aim.