In the interwar period, some military officers did not believe the combustion-engine vehicle would replace the horse for combat operations. Cavalry officers from around the world, including the United States and United Kingdom, argued strongly against trading their lovely mounts for new tanks. Many insisted that heavy armored vehicles could never conquer the hilly terrains in which horses thrived.In 1925, Field Marshal Sir Douglas Haig, the World War I commander in chief of the British Expeditionary Force on the Western Front, described the new airplanes and tanks as “only accessories” to warfare that would still be determined by “man and…