During the Franco-Prussian War, Paris was surrounded by the Prussians and the French attempted to use balloons to smuggle messages and supplies in and out of the besieged city. In response, Krupp developed a 37 mm cannon which was mounted on a pedestal which sat on a four-wheeled horse cart and was designated ' or "BaK" and this was the first practical anti-aircraft gun. Even though armed aircraft were used as early as the Italo-Turkish and Balkan Wars the designation "BallonabwehrKanone" remained in use until replaced by the more familiar "FlugabwehrK"'anone" or FlaK later in the First World War.