President Eisenhower was an Army officer in 1918. Got disgusted with the muddy, bottomless French roads, which were the same kind of roads we had in the US at the time. When he was back in Europe in WWII, found the French had not improved things greatly, but when in Germany was astounded at the Autobahns divided 4 lane highways, all paved. When he got the presidency in the 50s, he pushed hard for the Interstate highway system, also known a the Defense highway system. The military trucks that had 4x4 in 1918, The Jeffrey quad, and the Militor, left such an impression on the men, that the Jeep and 6x6 trucks were readily accepted in WWII.