Relying on motorized vehicles in addition to horses and mules for military use is different from building tactics and strategy around mechanized units. This article from 100 years ago in Scientific American was written when the First World War was raging in Europe and on the high seas, and the United States was nervously looking to its small armed forces and contemplating what might happen if the country should have to enter the war.
The article is about one modest experiment, but the first of its kind: a gun battery was moved the 134 miles from Los Angeles to San Diego. But the implications were great. The technical and tactical part was easily explained:
“Proving the great superiority of motors over mules for the hauling of coast defense artillery, the motor truck train of Battery A, Los Angeles [California] National Guard, recently made a 134-mile run along the Pacific Coast from Los Angeles to San Diego and maintained an average speed of 20 miles per hour, thus making in an hour's time by motor truck what would ordinarily be an entire day's trip for mules. It is said that the train, America's first organized volunteer motor reserve corps, hauled the battery a farther distance and at a greater speed than ever before accomplished over an American road. .... If horses had been used to make the 134-mile run it would have taken at least two days, and then under such extraordinary severe conditions that both horses and men would have been worn out before going into action.”
An officer’s car and five borrowed trucks carried 50 men and hauled four 3-inch field guns and their ammunition for the seven-hour trip. Captain Jesse McComas of the battery noted one conclusion:
“ ‘We moved the entire battery to San Diego and returned without a mishap and this is a feat because of the speed maintained. The guns are mounted on carriages built for shorter and slower horse travel. For long-sustained speeds the carriages should be mounted on rubber-tired wheels similar to those used on motor trucks, but the ones employed nevertheless stood up remarkably well despite the steady running.’ ”
A wheel is only as good as the road it runs over. The article goes on to point out the usefulness of having good roads that could carry military traffic in times of emergency:
“Much of the success of the demonstration, insofar as the speed maintained is concerned, was due to the excellent road over which the run was made. It skirts the coast between Los Angeles and San Diego and is solid concrete for almost the entire distance, being a perfect military road. It is called the King's Highway today, but its history dates back to the time of the Spanish occupation of lower California, when it was called EI Camino Real .... It is a shining example of the value of military roads along both our coasts and the facilities they would extend to American legions in case of war.”
In the lead-up to the First World War, railroads were built by Germany, France and Russia for strategic reasons: their purpose was to reduce the time it took to rapidly shift large numbers of troops around to where they were most needed. It is possible that the confidence this inspired in friendly armies, and the fear inspired in potential foes, may have been one of the reasons the Great War erupted so violently in the first place. In later years, good roads strong enough for military transport were constructed throughout Germany prior to the Second World War; one U.S. president took note of the commercial and military usefulness of these roads, and in 1956 commenced building the “Dwight D. Eisenhower National System of Interstate and Defense Highways,” otherwise known today as the Interstate System.
Our full archive of the war, called Scientific American Chronicles: World War I, has many articles from 1914–1918 on the technology of the First World War. It is available for purchase at www.scientificamerican.com/products/world-war-i/