By August 1915 the first tank prototype—“Little Willie”— was produced. Unarmed, it weighed eighteen tons, was top heavy and had a low ground clearance. More importantly, it could not cross an eight-foot gap—the width of a trench, which was one of its major requirements. It was soon discarded. The second prototype was called “Big Willie” or “Mother,” which changed from the box shape of “Little Willie,” to the now familiar lozenge-shaped vehicle. By 1916, testing on this armored vehicle was complete and considered so successful that an initial order for one hundred tanks was placed.