Use of the term "friendly" in a military context for allied personnel started during the First World War, often when shells fell short of the targeted enemy. The term "friendly fire" was originally adopted by the United States military; S.L.A. Marshall used the term in "Men Against Fire" in 1947. Many North Atlantic Treaty Organization (NATO) militaries refer to these incidents as blue on blue, which derives from military exercises where NATO forces were identified by blue pennants and units representing Warsaw Pact forces by red pennants. In classical forms of warfare where hand-to-hand combat dominated, death from a "friendly" was rare, but in industrialized warfare, deaths from friendly fire are common.