Staff Writer (Updated: 5/3/2016):
The basic half-track concept was originally showcased by the British in World War 1. By then, however, the combination of tracks an automobile-style wheels seemed impractical when fully-tracked or six-wheeled vehicles with four-wheel drive was favored. The half-track saw a comeback of sorts in the interwar years, primarily during the 1930's, where development peaked on both sides of the ocean. The German Army made extensive use of such vehicles in their route of enemy forces via the "Blitzkrieg" and the Americans took particular note of a French-made design known as the Citroen Kegresse P17. Such was the American interest in the French system that several of the French forms were purchased for additional hands-on testing and evaluation.
The P17 was soon spawned into the "T14" army half-track prototype of 1931. The T14 - produced primarily by the Army Ordnance Depot among others - was nothing more than a White Scout Car M2 series chassis melded to the Kegresse half-track suspension system. The resulting design proved adequate enough to become the newly-minted "Half-Track Car M2". Production of the Half-Track Car M2 was already underway by 1941 with Europe already embroiled in what would become known as "World War 2" since September of 1939.