Artillery - Inter-War
After the Great War, General John J. Pershing and others thought that the Army should be organized into small, highly mobile, hard-hitting units, but throughout the twenty-year period before World War II, the divisions remained slow, large, not particularly hard-hitting, and not well adapted for maneuver. Modern equipment and improved means of transportation were needed before smaller units could be made as effective as large organizations, but during the interwar period the Regular Army was small, and the necessary funds were not available. For field artillery, as well as for the division as a whole, the main problem lay in trying to balance the two important requirements of power and mobility.
Writing in the years immediately after the Great War, theorists blamed the artillery for the positional warfare that had developed and felt that the solution to breaking the stalemate lay in surprise and forward movement with emphasis on the tank and machine gun. In reacting against positional warfare, they stressed mobility, smaller units, and less artillery.
Suggestions for changes needed in the field artillery of World War I were incorporated in the report of the Hero Board, a board of officers named after its chief, Brigadier General Andrew Hero, Jr. Appointed on 9 December 1918 by the Chief of Field Artillery, the board studied the experiences gained by the artillery of the American Expeditionary Forces (AEF).
The same month Chief of Staff Peyton C. March, another former artillery officer, appointed a board of artillery and ordnance officers headed by Brigadier General William I. Westervelt to study the armament, caliber, types of materiel, kinds and proportions of ammunition, and methods of transportation to be authorized for a field army. The reports, submitted in early 1919, became the basis for field artillery development for the next twenty years.
The Westervelt Board, also known as the Caliber Board, based its recommendations on recent war experiences, relying heavily on the Hero Board's suggestions, the stocks of materiel on hand, and probable postwar reductions in appropriations. It classified the recommended materiel into two types: practical types for immediate development and ideal types for future development. As a basic principle, the board recommended that one of these types should ideally accomplish all the requirements of divisional artillery. Since such a solution was impractical, the board suggested that in addition to the 75-mm. gun, a light field howitzer such as the 105 be substituted for the 155-mm. howitzer in the division. Field artillery was supposed to be sufficiently mobile to neutralize the infantry of the opposing forces. The immediate targets were those obstacles preventing the advance of the friendly infantry. Close contact with the supported infantry, forward displacement with reasonable facility, and sufficient ammunition supply were necessary to accomplish the task. For these requirements the 155-mm. howitzer was too heavy, even though it was motorized. (Motorization had not yet reached the point where the howitzers were sufficiently mobile for divisional support in terrain where there were no good roads.)
After each arm or branch of service had evaluated its organization, a general board (known as the Superior Board) met to incorporate the recommendations on organization and tactics. In the meantime, the Organizational Section of the General Staff was preparing outlines for tables of typical divisions, corps, and armies, based in part upon those recommended by the Superior Board, but differing somewhat because of the growing belief that the AEF division (approximately 28,000 men) was much too large and unwieldy.
General Pershing, one of the critics of the cumbersome AEF division, felt that much of the Superior Board's report was based too heavily on the needs of positional warfare in Western Europe and not enough on a war of movement. Pershing thought the only way a mobile division could have its organic artillery with it at all times was to reduce the artillery permanently assigned to it. He suggested a division of 16,875 men that included one field artillery regiment of 75-mm. guns rather than three regiments of 75-mm. guns and 155-mm. howitzers. This would have reduced the number of divisional artillery weapons from the 72 of the AEF division to 36, and placed the general support mission with the corps rather than with the division. The division which the Organizational Section of the General Staff contemplated, on the other hand, had an approximate strength of 24,000 men and included one field artillery brigade of two 75-mm. gun regiments (48 guns). This plan conformed to Pershing's idea that the 155-mm. howitzer should be eliminated from the division, but differed in that it retained the artillery brigade structure.
Although the improved plan of 1920 called for the eventual replacement of the 155-mm. howitzer in the division by a new 105, there were those artillery officers who felt that the 75-mm. gun should be the weapon replaced. They argued that the latter gun could not reach an enemy positioned behind a good-sized hill because of its flat trajectory. Nor, for the same reason, could the weapon be placed behind a hill. In addition, the 75-mm. projectile was too small to be of sufficient power. During the war the United States and France had been the only major belligerents not equipped with a light field howitzer. Many artillery officers believed that from the standpoint of mobility, ammunition supply, and rate of fire, there were many advantages in adopting the light howitzer to replace the light gun.
In the 1930s European nations and Japan had reorganized their troops into smaller divisions, based on three infantry regiments rather than two brigades of two regiments each. There was a general trend to have weapons of heavier calibers than the 75-mm. gun in foreign armies. In January 1936 Chief of Staff Malin Craig appointed a committee to study the modernization of the Army. The tentative organization of the proposed division included one completely motorized field artillery regiment of one 105-mm. howitzer battalion for general support and three direct support battalions, each with two 75-mm. howitzer batteries and one 81-mm. trench mortar battery.
Brigadier General Lesley J. McNair, commander of the 2nd Field Artillery Brigade of the 2nd Division, pointed out that the War Department reorganization committee had placed too great an emphasis on artillery in close support of the infantry. This emphasis was reflected in the number and organization of the 81-mm. mortars and the substitution of the 75-mm. howitzer for the 75-mm. gun. He believed that modern artillery had great power in the individual projectile and that the key to success lay in the massing of fires on decisive points. Rarely in war, he reasoned, would there be sufficient artillery to cover all points thoroughly and continuously; therefore, fire should be massed in succession on the most important targets. The procedure required centralized control, great flexibility in delivery, considerable range, and good communications.
Since many infantry officers still considered the 75-mm. gun unsatisfactory for close infantry support because of its flat trajectory and its small projectile, some hoped that if the 105 were ever introduced, it would replace the 75-mm. gun instead of the 155-mm. howitzer. Even though the United States showed increased interest in the 105-mm. howitzer, there were still too many 75-mm. guns (with ammunition) left from the Great War. As an economy measure, these weapons were being modernized with new carriages.
To bring about decisive action, concentrations over wide areas would be necessary, followed by offensives delivered by waves of divisions, each prosecuted to the limit of the fighting capacity of the infantry involved. To accomplish this result in the most satisfactory manner, it must be possible to pick up divisions intact, move them rapidly by night over great distances, deliver them in the theatre of offensive operations in such manner as to permit them to move into position under their own power, attack as a unit and continue the fight to the limit of the capacity of the infantry to endure.
This contemplated motorization and mechanization to the extent necessary to accomplish the result. Ordinarily the number of railroad trains necessary to concentrate Field Artillery is so great as to make it undesirable to employ railroad transportation except in a very limited degree in concentrations of the above character. For such concentrations horse-drawn and portée artillery as used in France is undesirable. Tractor-drawn artillery was thought to be the answer, the tractor and the gun transported in trucks and unloaded near the scene of action. This made an unsatisfactory load, too high for many railway undercuts and top-heavy for excessively curved roads. The noise of the tractor in hauling the gun to position would advise the enemy that a concentration was in progress.
To meet these and other objections, in 1933 Major General Harry G. Bishop, Chief of Field Artillery, sought to substitute for horses or tractors, existing types of commercial trucks available in quantity both in peace and in war, and thus to contribute to the solution of the problem of motorization for the 75mm guns. This effort resulted in the truck-drawn battery of 75mm guns. The solution appeared to be the best as yet worked out and offers an answer to the demand for field artillery so organized as to be able to travel rapidly by road, move into position over average terrain, echelon to the front in attack as rapidly as may be necessary to support successfully attacking Infantry, provide its own food and keep up its own supply of ammunition.
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