Two significant tank developments came out of the fighting of World War 1 (1914-1918): the British introduced their large, trench-crossing monsters through their collection of lozenge-shaped "landships" and the French developed the Renault FT-17, a light-class combat vehicle sporting its main armament in a fully-traversing turret. Both types were used by the Americans as they went to war in Europe in 1917 but work at home soon began under various brand labels to produce combat machines to supply the wartime demand.
One of these ventures became the "Skeleton Tank", a creation by Winona, Minnesota-based Pioneer Tractor Company in 1918. The tank was developed along the lines of the large British landships but was stripped of all possible weight producing what was essentially a "skeletonized" landship. The design interested the U.S. Army enough for the service to fund the project.
Construction involved iron pipes for support that were completely exposed along the sides of the hull and between the two track-and-wheel components. Other structural pieces were comprised of less-expensive and readily-available wood. The same over-under track arrangement common to the British types was but the large crews seen in the landship was reduced in the Skeleton Tank to just two.
With the weight savings achieved by stripping back structure, the Skeleton Tank could retain the mobility of the lighter FT-17 tanks and still cross over the trench-works dotting the European landscape. The Skeleton Tank certainly maintained the proper length for it at 25 feet and its overall weight was 18,000lb, comparable to the FT-17s load of 14,330lb. Power was served through a pairing of Beaver-branded 4-cylinder gasoline engines outputting 50 horsepower each. A road speed of 5 miles per hour was all that could be had from this machine but was on par with combat tanks of the period.
Inside there were cramped fighting conditions for the two crew and they were housed in an lightly-armored "box" at the center of the design (armor protection reached just 1/2"). Vision slits were provided but situational awareness remained poor. A rounded superstructure, acting as a turret, was fitted over the top of the main hull structure and this section housed the single 0.30 caliber machine gun that was to act as primary armament.
It was planned that the Skeleton Tank could be mass produced by the Americans stateside and shipped in ready-to-assemble kits to Europe. This work would be handled in France near contested frontlines to which then the vehicles could be sent directly into combat. However, the war ended in November of 1918 with the German surrender and the single completed example of the Skeleton Tank was all that was had of the project.
With no standing wartime requirement, the Skeleton Tank was never adopted nor produced and the sole experimental example ended its days as a display piece at the United States Army proving grounds (Aberdeen, Maryland).