Meet Barney Roos—One of Many Jeep Daddies Willys MB Some say that General George Marshall was the "Father of the Jeep" since he made the most noise about the American Army's need for an all-terrain vehicle after his mud-spattered experiences with mules and horses during World War I. While it's true that Marshall played a crucial role in the government's investment in a motorized vehicle to replace the horse and, in due course, approved the testing and production of the jeep,