Boirault machine

Schematical advance of a Boirault machine over a hole in the ground and a barbed wire barrier.

The first Boirault machine in this post-war L'Illustration in 1919. The bottom photograph is the Frot-Laffly landship.

One of the first attempts was made in France with the early experiment made with the Boirault machine, developed in 1914 by French engineer Louis Boirault, proposed to the French War Ministry in December 1914, and ordered for construction on 3 January 1915.[3] On 19 January a commission, headed by Sub-secretary of State of Inventions Paul Painlevé, was formed to evaluate the project.

The objective of the machine was flattening barbed wire defences and riding over gaps in a battlefield. The machine was made of huge parallel tracks, formed by six 4x3 meter metallic frames, each with four transverse beams, so that it could also be described as a single track covering the entire width of the vehicle, rotating around a triangular motorized center,[3] and driven via chains and rods by an 80 hp petrol engine.

This device proved too fragile and slow however, as well as incapable of changing direction easily, as was indicated by a report on 17 May. The project was officially abandoned on 10 June 1915.[3] Upon the insistence of the inventor, modifications were made, a new commission was formed and new trials organized on 4 November 1915,[3] for the benefit of the Engineer Arm. The machine, loaded with nine tonnes of simulation weights, successfully flattened an eight metre wide barbed wire obstacle, overcame a funnel with a diameter of five metres and crossed a trench two metres wide. It reached a speed of 1,6 km/h. A second test on 13 November showed however that it was still extremely difficult to change direction. The whole assembly had to be lifted by a main jack, after which it could be turned for a maximum of 45° by hand from the outside or by a system of smaller jacks from the inside of the machine. Again the project was rejected, because of its visibility, noise, vulnerability, low speed and lack of manoeuvrability. Military historian Lieutenant-Colonel André Duvignac concluded that those that had baptised it Diplodocus militaris (after a giant sauropod dinosaur, well known at the period) "were not only poor humorists but also good judges".[5]

Boirault machine (No2)
Second Boirault machine, with Paul Boirault standing (bottom).
Place of origin	France
Service history
In service	August 1916 (experimental)
Wars	World War I
Production history
Designer	Boirault
Designed	1915–1916
No. built	1
Specifications
Crew	3 (estimated)
Maximum speed	1 km/h

A new model was developed, more compact and lighter, with armour for the engine and the driver compartment. It was composed of six metal plates rotating around the core chassis, and had some level of steering control, allowing for a turning radius of 100 meters. Speed however was extremely low, at 1 km/h. The new model was tried by the Artillery Arm on 17 August 1916 at Souain-Perthes-lès-Hurlus, until complete abandonment of the project.[3]

General Henri Gouraud commented on the performance of the machine on 20 August 1916, explaining that it ran for 1,500 meters in flat terrain, at about 1 km/h. It managed to cross a railroad, flatten a line of barbed wire, and crossed trenches 1.5 and 1.8 meters wide, and a hole two meters in diameter.[3]

General Gouraud commented on the sheer strength of the machine, but its poor ability to properly steer itself:

The steering is imprecise (...) Consequently, while the machine is capable of flattening everything in its path, it cannot be affirmed that it will be able to meet with certainty any given enemy organisation of limited dimensions that may be assigned to it, such as a bunker, machine gun housing, observatory... The trials, conducted far from the enemy, on a training ground, under conditions that in no way reflect reality, are far from conclusive."

— General Gouraud, 20 August 1916.[6]