Improvised vehicle armour is protective materials added to a mobile platform such as a car, truck, or tank in an irregular and extemporized fashion, using available materials. Typically, improvised armour is added in the field and it was not originally part of the design, an official up-armour kit, nor centrally planned and distributed. Improvised armour is used to protect occupants from small arms, crew-served weapons and artillery (or tank) fire, and mines. Improvised additions have included metal plate, scrap metal, sandbags, concrete, wood, and, since at least the 2000s, Kevlar. These materials vary widely in their ballistic protection. Improvised vehicle armour has appeared on the battlefield for as long as vehicles have been used in combat. In World War I, the first armoured cars were made by adding metal plating to regular vehicles. In World War II, tank crews of many armies attached spare metal tracks to the hulls and turrets of their tanks. In the Vietnam War, U.S. "gun trucks" were reinforced with sandbags and locally fabricated steel armour plate. In 2003–2011, U.S. troops in Iraq armoured their Humvees and various military transport and support vehicles with scrap materials: this came to be known as "hillbilly armour" by the Americans, or sometimes "hajji armour" when installed by Iraqi contractors. Irregular forces, guerrilla fighters, and other militants have also added improvised armour to vehicles. In the 2011 Libyan War, anti-Gaddafi militants used improvised armour on technicals (pickup trucks with machine guns or other crew served weapons). While most of this article is about military applications, there has been some non-military uses, such as protecting strikebreaker buses. World War I The first armoured cars to see combat were entirely improvised, although this soon changed as the war continued. A few were used by the Belgian Army during the German invasion. The British Royal Naval Air Service received reports of this and converted some of their own cars. Improvised conversion continued until December 1914 when the first standardized design entered service. The British Royal Naval Air Service in Dunkirk sent teams in cars to find and rescue downed reconnaissance pilots in the battle areas. They mounted machine guns on them and as these excursions became increasingly dangerous, they improvised boiler plate armouring on the vehicles provided by a local shipbuilder. World War II Most armies involved in the conflict adopted some form of improvised armour at some point. The Home Guard in