This thesis traces the development of combined arms concepts and organization by examining Great Britain, Germany, France, the US, and the USSR. It focuses on developments at and below division level, and provides information for the process of force and doctrinal design. Before 1914, the combat arms were integrated within the divisions of most armies. Each existed in small units equipped with one type of weapon and having limited interaction with the other arms. World War I not only witnessed the growth of modern indirect fire techniques and infantry organizations, but also forced armies to develop elaborate command, control, and communications systems to orchestrate the various arms on a battlefield. Germany synchronized its developments in materiel, doctrine, and training so that it had a temporary advantage in mechanized warfare during the period 1939-41. Most armies adjusted their armored formations from a tank-heavy structure towards a relatively balanced combination of infantry, armor, antitank, and artillery elements. They tried solutions to the problem of task organizing at the small unit and division level, and experienced difficulties in coordinating close air support. The USSR and the US have had to adjust to challenges posed to mechanized combined arms by the rise of nuclear weapons and of low intensity warfare. The themes of this thesis are: the necessity for combined arms integration at small unit level, the difficulties of achieving such integration by attaching non-divisional units on a temporary basis, and the continuing difficulties in reconciling ground and air force priorities in order to ensure effective close air support. (author).