On June 30th, 1915, trials of the Killen-Strait tractor, the basis of the first ever tank, were carried out at the Wormwood-Scrubs proving grounds.
The Killen-Strait farm tractor was produced in America since 1910. A unique feature was the presence of three tracks. The front track was for steering, and the two rear ones for propulsion. The tracks were also unusual. They were composed of hardwood and held together with chains. In order to reduce the amount of wear, the working surface of the tracks was covered in metal sheets.
The Killen-Strait possessed respectable maneuverability and off-road performance. The tilted rear tracks allowed it to back up over obstacles impassable for other tractors that were considered as a base for tanks. Killen-Strait's performance was noticed by Colonel Crompton, the representative from the Committee of Land Ships (an organization participating in the creation of first British tanks).
Sadly, trials showed that the tank cannot be used as a base for a viable prototype. It was too light to tear barbed wire, and had to cut through them, which took more time and could not always be attempted. Aside from that, the hull of the Delano-Belleville armoured car on top of its chassis made the vehicle too tall, and an easy target for enemy gunners.
Despite the fact that the tank was not mass produced, it remains in history as the very first tank, preceding the Little Willie or the MkI.
Original article available here.