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The US Army at the Start of World War II
Battalion: An Organizational Study of United States Infantry
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The estate of the late John Sayen has graciously given permission to the Tactical Notebook to serialize his study of the organizational evolution of American infantry battalions. The author’s preface, as well as previously posted parts of this book, may be found via the following links:
The US Army entered the Second World War in the fairly confident expectation that ground combat forces in general and the infantry in particular would have a much smaller role to play than they had in the First World War. The war in the Pacific would be primarily naval in character and in Europe there was hope that the Anglo-American strategic bombing campaign would bring Germany to its knees at a relatively low cost in lives and without the need for an extended land campaign. Early reports about the 1940 French Army being overwhelmed by hoards of German tanks and clouds of German dive bombers were given far too much credibility and prompted plans to create vast numbers of tank, tank destroyer, and anti-aircraft units to counter these exaggerated threats. Even after cooler councils had prevailed, considerable doubt remained about how useful conventional infantry was going to be. It was only late in the war that the Army realized that it needed far more of it than it had planned for.
Once it had established the infantry’s basic organizational framework the War Department was reluctant to make further changes beyond what was needed to incorporate new equipment and new ways to conserve manpower. Tactical organization was closely linked to doctrine and significant innovations to one almost invariably meant a ripple effect on the other. In an army of long service professionals who would have the time and experience to adapt themselves to new ways, major changes might have been practical. In an army of conscripts, however, whose members scarcely had time to learn one organizational-doctrinal system, major change could produce large-scale confusion.
Tactical organization was also critically important for mobilization and other preparatory planning. Tactical units were the building blocks with which the wartime army would be assembled and from on which the Army’s troop basis would largely be determined. Training, much of it little more than the inculcation of doctrine, would also be profoundly affected by organizational change. Consequently, the War Department was keenly aware of the need to establish sound wartime organization and doctrine well in advance. Hence, the rush of testing and experimentation with infantry organizations from the mid-1920s onward to get the Army ready for its next European war.
Nevertheless, there was still room for some innovation, especially while the ground forces’ buildup was still in its early stages and the new recruits were not yet wedded to any particular system of doing things. In order to incorporate the lessons learned in the 1941 maneuvers as well as the new equipment that was at long last becoming available, the Army launched a general reorganization of all its combat units in April 1942. Combat experience did not influence this reorganization. The Regular Army regiments stationed in the Philippines had been fighting the Japanese since December 1941 using essentially the December 1938 tables, diminished somewhat by manpower and equipment shortfalls. The regiments of the newly organized Philippine Army also attempted to follow the 1938 tables but were in much worse shape in terms of both equipment and readiness. That the defense of the Philippines ended in disaster was far more a consequence of high level indecision and a general lack of preparation than it was the result of any defective tactical organization. In any case, few details of these early battles became available until after the survivors had emerged from Japanese prison camps in 1945.
The new weapons and equipment that helped to bring about the April reorganization included a hollow charge rifle grenade called the M-10 which offered much better armor penetration than any previous infantry weapon. In order to use the M-10, the Army would have to bring back its rifle grenade launchers but these could also fire the new fragmentation rifle grenades that would soon be available. Such developments finally led the Army to agree with the Marines that, despite its excellence as a company support weapon, the 60mm mortar could not replace the rifle grenadier. However, the M1 rifle still had no grenade launcher so the M1903 rifle would have to be reintroduced to make its launcher available for the M-10. Soon, the lighter but still effective M9 grenade would replace the inconveniently heavy M-10. Rifle grenade launchers (with M1903 rifles) would be issued to infantry units at all echelons to provide local antitank defense.
A second major innovation was the M1 carbine. Like the M1919A4 light machine gun this weapon had a prolonged development and began to appear in tables of organization long before it was actually available. It was intended as an ultra light semi-automatic rifle that would replace all .45 caliber pistols except for those carried by “field grade” officers (majors and above) and by the gunners and assistant gunners in most machine gun and mortar squads. The carbines would also replace some rifles, including those carried by senior enlisted men (mainly first sergeants and sergeants major), and company buglers, messengers, and communication personnel. Rifle platoons continued to use mostly rifles but weapon platoons switched completely to carbines except for their squad leaders and basic privates. Antitank platoons also issued rifles to drivers and their liaison and transport corporals.
The final development in infantry weapons during the early months of the war was the increased production of M3 37mm antitank guns. This allowed .50-caliber machine guns to be retired as antitank weapons and to instead become convoy defense weapons. Fired from a ring or pedestal mount the .50-caliber was normally carried by the new 2.5-ton 6x6 cargo trucks to give anti-aircraft protection.
Robert R. Palmer “The Reorganization of Ground Troops for Combat” in Kent Roberts Greenfield and others The U.S. Army in World War II - The Organization of Ground Combat Troops (Washington DC: Office of the Chief of Military History 1947) pages 265-67
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