This paper discusses the US Air Force/Bell Aircraft Corporation X-2 project which began in 1945. It was aimed at developing a research aircraft designed to reach speeds of over Mach 3 and altitudes over 100,000ft. A brief description of the aircraft is given along with a discussion of its flight test programme. The much-delayed project ended on 27 September 1956 during the aircraft's 13th powered flight. Loss of control at over Mach 3 led to violent motions characteristic of inertia roll coupling, following which both pilot and aircraft were lost. The paper concludes with an examination of the limited achievements of the project and lessons learned from it.