Christie then entered the automobile industry, building his own cars and testing them in speedway races. Among his designs was a front-wheel-drive car. He also invented a steam-engine, piston-packing ring that was used in ferryboat engines. In 1912, Christie began manufacturing wheeled tractors to pull fire-fighting equipment, selling several hundred to New York City alone.
In 1916, Christie designed a four-wheel-drive truck for use by the military in the rugged terrain of the southwestern United States in the event of trouble with Mexico. That year, the army contracted with his Front Drive Motor Company for a motor carriage for a self-propelled, 3-inch gun. During World War I, Christie became interested in tank design. The first of some 15 designs for the army was for a "convertible," self-propelled, 8-inch gun that could operate either on tracks (for cross-country mobility) or at a higher speed on its own road wheels. It was produced as a single prototype in 1921 but failed to meet army design specifications, beginning what would be an acrimonious relationship between Christie and the Ordnance Department.
This experience led Christie to design the first American postwar tank, the 3-man, 13.5 ton Medium Tank M1919, with a removable track that could be stored around the tank hull during road operations. The M1928 was powered by a Liberty aircraft engine and had both great speed and a revolutionary suspension system of large, weight-bearing wheels on torsion bars. The army ordered five M1928s. This vehicle was highly influential in tank design abroad, first in the USSR and then in Britain. The Soviets acquired two copies and used the M1928 as the basis for their BT-series. Their T-34 tank, which employed the Christie suspension system, may have been the best tank of World War II.
The U.S. Army purchased three M1931 (U.S. designation, T-3) Christie tanks, and the Soviets bought two. The vehicle was armed with both a 37 mm gun and a machine gun. Christie's M1932 employed light-weight materials and had a forward-facing propeller so that it could be dropped from a low-flying aircraft, fly, and hit the ground running. It could make road speeds of 36 mph on tracks or 65 mph on wheels, enabling it to leap a 20-foot gap from a 45-degree ramp. It was also sold to the Soviets. Christie's M1936, a 6 ton, 2 man tank, was capable of cross-country speeds of up to 60 mph. In Britain, it evolved into the first Cruiser tank.
For the United States, Christie also designed turret tracks for battleships, as well as gun mounts and carriages. His amphibious platform for a 75 mm gun, begun in 1921, led to the first amphibious tank. Never fully appreciated in his own country, in part because of his acerbic and combative personality, Christie died penniless and embittered in Falls Church, Virginia, on 11 January 1944.
Robert Bateman and Spencer C. Tucker
Hofmann, George F. "Christie's Last Hurrah." Armor (November-December 1991): 14–19.; Hofmann, George F. "Army Doctrine and the Christie Tank: Failing to Exploit the Operational Level of War." In George C. Hofmann and Donn A. Starry, eds., Camp Colt to Desert Storm: The History of U.S. Armored Forces, 92–143. Lexington: University Press of Kentucky, 1999.