 German blitzkrieg in Poland and France compelled the military leadership in favor of armoured warfare, and the United States cavalry was mechanized contrary to Herr's objections.General Robert W. Grow wrote that "had General Herr, from the beginning, taken a strong stand to mechanization of the Cavalry Branch, the Armored Force would have never been created" (as a separate combat arm).Instead, Herr "lost it all"