Cold War Tank Evolution: From M46 Patton to the Controversial M551 Sheridan The Cold War era saw a radical shift in American armor, starting with the M46 Patton in 1949. Reaching 30 mph, it served as a vital bridge between WWII and the modern era. However, the search for a versatile, air-droppable scout led to the controversial M551 Sheridan in 1966. Capable of hitting 43 mph, the Sheridan featured a unique 152mm gun/missile launcher. While innovative, its thin aluminum hull and technical glitch