The following document is an internal War Department General Staff memorandum that outlines key mechanization policy decisions. It summarizes the principal events leading from the Experimental Mechanized Force of 1928 to the Armored Force in 1940. While the memorandum’s intent lay in tracing the views of the War Plans Division, it nevertheless provides a sensing of interwar mechanized development in the U.S. Army from a War Department perspective. Note, however, that there is no reference to the mechanization guidance issued in 1935.
In 1931 U.S. Army Chief of Staff General Douglas MacArthur broadened mechanized development to include combat arms other than just Infantry. He believed the importance of the tank transcended the close infantry support role of World War I, and he sought to create the conditions for more general experimentation and development of mechanization. In 1928 the Army established the temporary Experimental Mechanized Force to explore the employment of an all-vehicle organization in a variety of roles. In 1930, the Army created the Mechanized Force to develop principles and concepts for further mechanized development. However, this organization met with general opposition from the branch chiefs and proved expensive. Plans for future development of the Mechanized Force required a significant, sustained investment. As the Great Depression intensified and the probability of increased military spending fell, MacArthur had to decide whether to concentrate Army resources on the high tech but expensive Mechanized Force or the retention of Regular Army personnel. He chose personnel over technological development, and the Mechanized Force disbanded. However, MacArthur realized the importance of encouraging mechanized development throughout the Army. He therefore issued the following guidance for mechanization. While the Infantry retained its tank force, the new policy permitted the application of mechanization to the broad array of cavalry missions. To avoid violating the letter of the National Defense Act of 1920, which exclusively assigned tanks to the Infantry, tanks assigned to cavalry organizations would be designated “combat cars.” Consequently, the Army pursued two separate mechanized development paths in the 1930s, symbolized by the Infantry tank force and the 7th Cavalry Brigade (Mechanized).
The attached manual was originally compiled in 1933 and reprinted in 1936. It constituted the Cavalry School’s doctrinal guidance for the newly established mechanized cavalry. At the time of its initial printing, the 1st Cavalry Regiment (Mechanized) was in the earliest stages of development and lacked doctrinal support. No precedent existed for an entirely mechanized cavalry organization, and this manual helped to fill that void. It applied traditional cavalry principles to an all vehicle organization, effectively creating a baseline for further mechanized cavalry development. By the time of the reprint in 1936, however, the 7th Cavalry Brigade (Mechanized) had expanded and evolved beyond the basic concepts here. Moreover, the absence of any mechanized assets at the Cavalry School on Fort Riley, Kansas, limited the degree of effective guidance that could be offered. Instead, the 7th Cavalry Brigade (Mechanized) at Fort Knox became the driving force for mechanized cavalry employment principles and doctrinal concepts.
Evolution of the mechanized cavalry triggered a War Department update to the original 1931 mechanization policy. In general terms, mechanization continued to be encouraged in all Army branches. By 1935, however, mechanized cavalry development at Fort Knox matured sufficiently for implementation of the next phase of its evolution, which entailed an expansion of capabilities. The mechanized cavalry included the 7th Cavalry Brigade (Mechanized), the 1st Cavalry Regiment (Mechanized), and the recently attached 1st Battalion, 68th Field Artillery. The 1935 policy refinement gave special attention to this artillery unit, its training, and its ability to integrate its actions with those of the mechanized cavalry. Primary responsibility for overseeing the expanded mechanized cavalry lay with the V Corps Area commander rather than the chief of Cavalry. This assignment reflected the expanded nature of the 7th Cavalry Brigade (Mechanized), which through the attachment of field artillery, no longer included only cavalry assets. It also tended to erode the chief of Cavalry’s development influence upon the Army’s most modern mounted unit.
The War Department offered additional guidance for mechanization in 1938. It emphasized the leading roles played by the infantry tank force and the mechanized cavalry, although mechanized development by other branches was not curtailed. For the mechanized cavalry, this updated guidance outlined its basic missions, emphasized its unique mix of firepower and mobility, and provided basic doctrinal principles. While the mechanized cavalry was intended for broad ranging and independent missions, the War Department expected tanks to operate in close proximity to supported infantry and to be employed in successive echelons reminiscent of their intended role in World War I. Tanks constituted an auxiliary weapon to support the infantry mission. These basic differences between infantry tanks and mechanized cavalry resulted in very different development paths. In training and exercises, the Infantry focused upon coordinated action between tanks and riflemen at the small unit level, while the 7th Cavalry Brigade (Mechanized) emphasized fast paced, decentralized operations that ranged much further in time and space.
General Van Voorhis earned the title “grandfather of the Armored Force” for his leadership of the mechanized developments in the 1930s. He commanded the Mechanized Force, responsible for testing the applicability of an all-vehicle combat organization to a variety of missions other than infantry support. When the Mechanized Force disbanded and the mechanized cavalry was established, Van Voorhis commanded the 1st Cavalry Regiment (Mechanized) and later the 7th Cavalry Brigade (Mechanized). By 1938 he had risen to major general and commanded the V Corps Area, which included developments at Fort Knox, Kentucky, home of the mechanized cavalry. The attached file is a transcription of a briefing on mechanization he presented in September 1938 to the Army War College and the related question and answer session. Van Voorhis outlined the history of American mechanization since World War I with an emphasis upon the development of the 7th Cavalry Brigade (Mechanized). He discussed the mission, basic principles of employment, materiel, and characteristics of mechanized cavalry. He also advocated an expansion of the 7th Cavalry Brigade (Mechanized) into a division and the related capabilities such a formation required. Beyond mechanized cavalry, Van Voorhis supported the inclusion of mechanized reconnaissance in infantry divisions, the development of tank battalions intended for assignment to assault troops as necessary, and a heavy, combined arms “shock” division. His ideas were shaped by his own experience with American mechanization and analysis of foreign trends, which are summarized in this presentation.
The following document is a transcription of BG Adna Chaffee’s briefing on mechanized cavalry presented at the Army War College in September 1939. It provides Chaffee’s view on mechanized development to date, the composition and basic principles of employment of the 7th Cavalry Brigade (Mechanized), and his recommendations for further expansion of the mechanized cavalry. This briefing was presented in the wake of the First Army maneuvers of August 1939, in which the 7th Cavalry Brigade (Mechanized) demonstrated its potential as a decisive battlefield influence. The employment principles demonstrated during these maneuvers found validation in the successful use of German armored, combined arms formations during the invasion of Poland that began shortly after the conclusion of the First Army maneuvers. Chaffee saw the success of German panzer as confirmation of the mechanized cavalry’s evolutionary path. He therefore sought an expansion of the capabilities represented by the 7th Cavalry Brigade (Mechanized). Many of the ideas represented in this briefing, particularly his emphasis upon reconnaissance, rapid communication and decision making, and the employment of the mechanized cavalry as a mass of decision, found reflection in the later armored division and related doctrine. At the time of this presentation, Chaffee commanded the 7th Cavalry Brigade (Mechanized). Previously, he had studied mechanization trends for the War Department G-3, served in the Mechanized Force, and commanded the 1st Cavalry Regiment (Mechanized). By late 1939, he had emerged as a leader in American mechanized development.
On July 10, 1940, the War Department directed the creation of the Armored Force. The specific guidance issued to establish this new organization is presented in its entirety in the following pages. Note that the Armored Force was depicted as a service test. This nomenclature permitted the Army to create this organization on its own authority without an act of Congress. As a service test, the Armored Force could rapidly begin building the armored capability desired by the Army. The new organization possessed many of the same powers associated with the existing combat arms, but it was not an official branch. Consequently, the Army could and did alter the structure and responsibilities of the Armored Force throughout World War II. Only in 1950 with passage of the Army Organization Act did the Armor Branch acquire the legal foundation and permanency of the other combat arms. The enclosure included with the following document describes the original organization and personnel composition of the armored division. This new formation reflected the availability of resources in July 1940 and a deliberate attempt to model it upon the German panzer division, which had played a prominent role in the Polish and French campaigns.