the circumference. The machine was to be mounted on four wheels which would be turned by the crew through a system of hand cranks and cage (or "lantern") gears. Leonardo claimed: "I will build armoured wagons which will be safe and invulnerable to enemy attacks. There will be no obstacle which it cannot overcome." Modern replicas have demonstrated that the human crew would have been able to move it over only short distances. War wagon Hussite forces in Bohemia developed war wagons – medieval horse-drawn wagons that doubled as wagon forts – around 1420 during the Hussite Wars. These heavy wagons were given protective sides with firing slits; their heavy firepower came from either a cannon or from a force of hand-gunners and crossbowmen, supported by light cavalry and infantry using pikes and flails. Heavy arquebuses mounted on wagons were called arquebus à croc. These carried a ball of about . Armed and armoured car The first modern AFVs were armed cars, dating back virtually to the invention of the motor car. The British inventor F. R. Simms designed and built the Motor Scout in 1898. It was the first armed, petrol-engine powered vehicle ever built. It consisted of a De Dion-Bouton quadricycle with a Maxim machine gun mounted on the front bar. An iron shield offered some protection for the driver from the front, but it lacked all-around protective armour. The armoured car was the first modern fully armoured fighting vehicle. The first of these was the Simms's Motor War Car, also designed by Simms and built by Vickers, Sons & Maxim in 1899. The vehicle had Vickers armour 6 mm thick and was powered by a four-cylinder 3.3-litre 16 hp Cannstatt Daimler engine giving it a maximum speed of around . The armament, consisting of two Maxim guns, was carried in two turrets with 360° traverse. Another early armoured car of the period was the French Charron, Girardot et Voigt 1902, presented at the Salon de l'Automobile et du cycle in Brussels, on 8 March 1902. The vehicle was equipped with a Hotchkiss machine gun, and with 7 mm armour for the gunner. Armoured cars were first used in large numbers on both sides during World War I as scouting vehicles. Tank In 1903, H. G. Wells published the short story "The Land Ironclads," positing indomitable war machines that would bring a new age of land warfare, the