Combat arms (or fighting arms in non-American parlance) are troops within national armed forces who participate in direct tactical ground combat. In general, they are units that carry or employ weapons, such as infantry, cavalry, and artillery units. The use of multiple combat arms in mutually supporting ways is known as combined arms. In some armies, notably the British Army, artillery and combat engineer units are categorized as combat support, while in others, such as the U.S. Army and Canadian Army, they are considered part of the combat arms. constitute a combat arm in name, although many have histories derived from cavalry units.