carriers (APCs) are intended to carry infantry quickly and relatively safely to the point where they are deployed. In the Battle of Amiens, 8 August 1918, the British Mk V* tank (a lengthened Mark V) carried a small number of machine gunners as an experiment, but the men were debilitated by the conditions inside the vehicle. Later that year the first purpose-built APC, the British Mk IX tank (Mark Nine), appeared. In 1944, the Canadian general Guy Simonds ordered the conversion of redundant armoured vehicles to carry troops (generically named "Kangaroos"). This proved highly successful, even without training, and the concept was widely used in the 21st Army Group. Post-war, specialised designs were built, such as the Soviet BTR-60 and US M113. Infantry fighting vehicle An infantry fighting vehicle (IFV), also known as a mechanized infantry combat vehicle (MICV), is a type of armoured fighting vehicle used to carry infantry into battle and provide direct fire support. The first example of an IFV was the West German Schützenpanzer Lang HS.30 which served in the Bundeswehr from 1958 until the early 1980s. IFVs are similar to armoured personnel carriers (APCs) and infantry carrier vehicles (ICVs), designed to transport a section or squad of infantry (generally between five and ten men) and their equipment. They are differentiated from APCswhich are purely "troop-transport" vehicles armed only for self-defencebecause they are designed to give direct fire support to the dismounted infantry and so usually have significantly enhanced armament. IFVs also often have improved armour and some have firing ports (allowing the infantry to fire personal weapons while mounted). They are typically armed with an autocannon of 20 to 57 mm calibre, 7.62mm machine guns, anti-tank guided missiles (ATGMs) and/or surface-to-air missiles (SAMs). IFVs are usually tracked, but some wheeled vehicles fall into this category. IFVs are generally less heavily armed and armoured than main battle tanks. They sometimes carry anti-tank missiles to protect and support infantry against armoured threats, such as the NATO TOW missile and Soviet Bastion, which offer a significant threat to tanks. Specially equipped IFVs have taken on some of the roles of light tanks; they are used by reconnaissance organizations, and light IFVs are used by airborne units which must be able to fight without the heavy firepower of tanks. Infantry mobility vehicle An infantry mobility vehicle (IMV) or protected patrol vehicle (PPV) is a wheeled armoured personnel carrier (APC)