Army Mechanization Before WW II

The potential of motorized vehicles and aircraft became obvious during World War I, but it was mostly just potential. The world was rapidly changing but vehicle technology and supporting infrastructure were not yet ready for mechanization of the U.S. Army. The decades between the two world wars saw rapid development of ideas and equipment, held back by budget limits and entrenched resistance to changes to the traditional roles of horses for cavalry missions and both horses and mules as pack animals. The resistance and budget concerns were quickly swept away by the advent of WW II. The animals were mostly retired and the fully mechanized force came into complete dominance of warfare.

Troop B, 252d Quartermaster Remount Squadron, unloading horses for the Third U.S. Army maneuvers, Camp Polk, LA, fall 1942
Troop B, 252d Quartermaster Remount Squadron, unloading horses for the Third U.S. Army maneuvers, Camp Polk, LA, fall 1942.

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Mechanization Lessons of WW I

A mule team, hauling a U.S. ammunition wagon, is holding up the advance of a mixed animal and motor column, east of St. Mihiel, France, 13 September 1918
A mule team, hauling a U.S. ammunition wagon, is holding up the advance of a mixed animal and motor column, east of St. Mihiel, France, 13 September 1918.

In many ways World War I resembled all past wars. Cavalry horses and pack animals were used in large numbers. For perspective, during the war, Great Britain shipped 5,253,538 tons of ammunition to France. But the greatest single item shipped was 5,438,602 tons of oats and hay, augmented by local forage.

But times were about to change. In 1912, the U.S. Army had purchased four commercial trucks. Early tests were not encouraging. At first, horses easily outclassed the limited and unreliable trucks of that time. But trucks rapidly improved and the days of horses were numbered.

World War I was the last major conflict in which the United States Army used horses and mules in significant numbers. The Remount Service was enlarged to meet the increased demands of the Artillery, the Cavalry and other units. Around 571,000 horses and mules processed through the Remount system of which more than 68,000 were killed in the war. At the close of the war the Quartermaster Corps maintained 39 remount depots with a capacity 229,200 animals. During WW I, American industry produced over 118,000 trucks of all types including the Standardized Class B (Liberty Truck), but only 51,554 were sent overseas.

During WW I, the truck, tractor, and a few tanks (as well as the airplane) showed the military potential of the new motor technology. The greatest example was at Verdun, where French Gen. Pétain's logistics had to support a force of 500,000 men and 170,000 animals. Each horse alone required forty pounds of fodder and eight gallons of water a day. No army of this size had ever been sustained and supported logistically by road, but the French Army successfully supported the battle by truck transport of men, ammunition, and other classes of supplies. They also made sound use of trucks returning from the sector by evacuating casualties as retrograde cargo. This experience validated the use of trucks, at least when a road system was available.

Cavalry officers saw that airplanes could provide reconnaissance over a wide area at little cost, at least in daylight during good weather. Motorcycles were found useful for dispatch riders and autos as a mobile base for commanding officers. Artillery experimented with trucks and tracked prime movers (tractors) for heavy guns.

There was no question of the superior qualities of the motor vehicle alternatives as a "laboratory" solution, but considerable doubt remained that horses could be replaced en masse, under all circumstances. The primitive trucks, tractors and cars of the time were not standardized, broke down frequently, and suffered from a lack of expertise in maintaining or operating them. By contrast, the horse was ready to go at any hour under all conditions (dark, flooded, wooded, frozen, etc.) whereas early vehicles lacked such flexibility, reliability and dependability. If a truck was out of gas, it was done whereas even a hungry horse could be urged onward.

Still, forward thinking officers knew that the motor vehicles would play an increasing role and began to investigate how far that role might extend. In the aftermath of WW I, motorization versus mechanization were alternative solutions to the problem of integrating the internal combustion engine into the armed forces. The former implied grafting automobile transport on to existing combat arms, while the latter called for the creation of "self-propelled combat means" with an emphasis upon armor, especially, tanks, armored cars, and self-propelled artillery.

Mechanization in the Interwar Years

Cavalry horses and mechanized forces intermix.  2nd Cavalry Troopers on horses going into the woods with a new 92nd Reconnaissance armored car in the foreground,  2nd Army Maneuvers in Louisiana, September 1941
Cavalry horses and mechanized forces intermix. 2nd Cavalry Troopers on horses going into the woods with a new 92nd Reconnaissance armored car in the foreground, 2nd Army Maneuvers in Louisiana, September 1941.

In the summer of 1919, the first Army transcontinental motor convoy tested the efficacy of the military vehicles then available. Eighty-one motorized Army vehicles, representing a variety of styles and manufacturers, crossed the United States from Washington, DC to San Francisco, CA, spanning a distance of 3,251 miles in 62 days (7 July to 6 September 1919). The expedition was manned by 24 officers and 258 enlisted men. The future General and U.S. President Dwight D. Eisenhower, then a Lt. Col., was along as an Observer. The roads were often impassable, and breakdowns of the military vehicles were frequent. Still, the convoy was a harbinger of things to come.

In the 1920s the U.S. was isolationist and budgets for the military were minimized. Funding to experiment with vehicles was very limited, often stolen from other projects by influential officers with the mechanization vision. Liberty Trucks left over from the Great War were used, or standard commercial vehicles, lightly modified to simulate new designs. Innovative work at Ft. Knox, KY on armored force concepts, Quartermaster development of automotive technology at Ft. Holabird, MD, and the evolution of Cavalry doctrine at Ft. Riley, KS moved the ideas and the machines along.

Still, rapid adaptation to change was not a hallmark of the U.S. Army in this period. At the Langley Field Tactical School, Hampton, VA, then the only school for Army aviation tactical training, as late as 1923 some 25 hours of the course were devoted to the care and management of horses.

By 1928, changes began to show in official actions. The "Provisional Platoon, 1st Armored Car Troop," was activated on 15 February 1928 at Fort Myer, VA The Army General Staff finally recognized the need to embrace mechanization, issuing a memorandum in March 1928 that explained how the mechanized force was intended to fit into the existing organization of the Army. At Camp Meade (now Fort Meade), MD, in July 1928, approximately 3,000 troops (including Provisional Platoon, 1st Armored Car Troop) took part in a test of light and medium tanks, motorized artillery and infantry, support troops, and even cavalry mounted in armored cars. Trucks were used extensively in support of the 1928 Maneuvers. The 8th Engineer Battalion used trucks to move about and prepare the maneuver area by marking gates, repairing roads, bridges and improving the ever-important water facilities. The infantry troops for the exercise traveled 223 miles by truck in three days to join the division. The attached A Battery, 1st Field Artillery was organized as a portee battery utilizing trucks and trailers to move the cannons and tractors to Fort D. A. Russell, TX, from Fort Sill, OK. The division also conducted an important exercise with portee cavalry.

The 1st Cavalry Division motorized its entire rear echelon for the exercise. The decision to motorize the logistics trains proved crucial. Distribution points for the units in the field were some 36 miles from the railhead and "the use of animal drawn trains exclusively under this situation would have been impossible" noted the closing remarks on supply and logistics. Trucks were embraced for their ability to extend the radius of operations for the division trains. Prior to including the use of trucks, animal drawn trains were only capable of supplying the division eight miles from the railhead.

Horses were still considered superior, the all weather, stream swimming, forested hillside traversing, night time operating, "any condition one can think of" mobility solution. Mechanized vehicles of the early 1930s were quite limited, but not as limited as opponents imagined. Roads in the United States in 1930 were just over six percent improved, the same in Europe and much worse worldwide. But the lessons of the 1928 Maneuvers and subsequent tests solidified the role of the mechanized elements of units, and later entire units, all at the expense of the horse and pack mule. In 1931, a new War Department policy, pushed by Chief of Staff Gen. Douglas MacArthur, directed that all branches of the services should mechanize. Some changes followed, but slowly, constrained by budgets and inertia. In 1931 new motorized units in the 120th Field Artillery replaced horse-drawn guns and caissons during summer training at Camp McCoy. In 1933, 1st Cavalry Regiment became the 1st Cav. Regt. (Mechanized), turned in its horses and moved to Ft. Knox, KY. Scout cars were accepted in 1935 with the M3A1 becoming the pre-war standard. While not every officer was convinced, and while budgets did not yet exist to scale up the implementation of the latest ideas, the horse and mule were soon to be pushed to the sidelines.

Mechanization was embraced, but slow to come into reality. On 19 April 1934, the first major test of the reorganized 1st Cavalry Regiment (Mechanized) took them from Ft Knox, KY to Ft Riley, KS for maneuvers, an exercise designed to pit the fully mechanized 1st Cavalry unit against Cavalry regiments in which mechanization was only a supporting element. The convoy column stretched out to eight miles long (one mile in close formation) with 189 vehicles (103 for supply and maintenance), 587 men and 37 officers. But there were only six of the new combat cars in the column. The deficiency was made up by 1 1/2-ton trucks, painted with yellow bands to indicate they were supposed to be combat cars. In the event, four of the combat cars broke down and had to be sent to Ft. Riley by rail. Nonetheless, the Ft. Riley maneuvers were a turning point, demonstrating that the mechanized units could conduct all the traditional cavalry missions, with an extended "sphere of action" that horses could not provide. The mechanized units did not suffer in direct confrontation with horse units. Extensive and detailed reports were issued that also noted that track-laying vehicles were clearly superior for essential cross-country mobility.

Gradually the central ideas of a new military reality emerged and became widespread by the late 1930s:

  • Cavalry: Mechanized reconnaissance experimentation continued during the 1930s, at first largely in support of horses. Wheeled armored cars with a small squad of soldiers and radios would augment horse cavalry for reconnaissance, working with aircraft and motorcycle messengers to locate the enemy, inform higher headquarters and fight if necessary. Full mechanization was resisted by old-line Cavalry officers right into WW II, but by the early 1940s mechanized reconnaissance was in full competition with horses.
  • Artillery: Tractors or trucks as prime movers would enable larger field guns, faster deployment, faster change of position, and better ammunition supply but the Army had difficulty finding trucks up to the job. Tractors could pull the guns but were too slow. Fears that trucks could not operate in adverse terrain, cross country, kept horses in at least some of the artillery regiments as late as 1939. For light artillery, that had to accompany infantry everywhere, including forests and flooded areas, the question remained open until the jeep appeared in 1940 as a fully capable replacement for the horse.
  • Supply: For the Quartermaster, trucks were clearly the way to go for all except the most demanding terrain. Trucks were cheaper to fuel and maintain, were steadily improving in off-road capability, had greater range and capacity, and were easier to train troops to operate and repair. The latter point was due to changes in American civilian society where the horse was rapidly being replaced by cars and trucks.

Horses in Twilight as World War II Dawns

Although Army Air Corps officers were required to wear spurs until the late 1930s, the U.S. Army had absorbed the concepts of mechanization by then. There had not been sufficient progress and many vestigial remnants were still embedded in place, but that would quickly change under the stress of total mobilization for total war.

After the opening of World War II in Europe, with the German invasion of Poland in September 1939, the huge expansion of the U.S. Army began in earnest. The experimental mechanization ideas were integrated into practice and large scale procurement of vehicles was underway. News from the war zones was grim. The Blitzkreig in Europe made a mockery of outdated concepts from prior wars. The slaughter of Polish Cavalry, facing the Wehrmacht tanks and Luftwaffe dive bombing planes, eliminated any thought of a continuing role for the horse in modern combat. Counterexamples were few and fully mechanized units quickly grew in number at the expense of horse units. In 1941, field manuals were revised to focus on mechanized units with most of the old horse cavalry material minimized or eliminated.

The 1st Cavalry Regiment, as a member of the 7th Mechanized Brigade, was the showpiece of American Armor. The German use of massed armor finally shook loose the blocks to the expansion of American Armor. As a result, on 15 July 1940, they were reorganized and re-designated as 1st Armored Regiment, an element of 1st Armored Division. Reconnaissance was the only mission remaining for mechanized cavalry after the creation of the Armored Force in 1940.

Portee cavalry in use during the 1940 General Headquarters Maneuvers. The special built tractor-trailers were capable of rapidly transporting eight fully equipped Troopers with their horses to any staging point. The Cavalry Journal, September-October 1940
Portee cavalry in use during the 1940 General Headquarters Maneuvers. The special built tractor-trailers were capable of rapidly transporting eight fully equipped Troopers with their horses to any staging point. The Cavalry Journal, September-October 1940.

Still, the horse had its defenders, especially Major General John K. Herr, the last Chief of Cavalry. One aspect of this defense was continued testing of portee Cavalry, the use of trucks to move fresh horses to the battle where Troopers would mount up and operate as traditional horse cavalry. Even when successful in maneuvers, such efforts were a last gasp. The resistance of the Cavalry to full mechanization and corresponding doctrinal changes left Cavalry weaker than necessary for actual combat as encountered in North Africa and Sicily.

Mechanized units ultimately did take over all of Cavalry Branch's traditional missions, including both combat and reconnaissance, but it took the experience of World War II for mechanized doctrine and organization to fully restore Cavalry Branch's identity as a combat arm. But the horses were gone for good as horseflesh gave way to iron steeds. Cavalry Branch was eventually renamed Armor Branch in 1950.

Portions of this page adapted from Men on 'Iron Ponies,' The Death and Rebirth of the Modern U. S. Cavalry, by Matthew Darlington Morton, Ph.D. Thesis, 2004, History Department, Florida State University. Also available in book form from Amazon.

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