[1] The immobility of the trench warfare characterizing the First World War led to a need for a powerfully armed military engine that would be at the same time protected from enemy fire and could move on the extremely irregular terrain of battlefields.

Barbed wire especially posed a considerable threat as it was cheap and easy to install, extremely effective at slowing or stopping an offensive by troops against protected fire, and very difficult to eliminate, even with artillery.

The use of caterpillar tracks was discussed that same month, but since none was available at that time, the system was then mounted at Liancourt on the back of a Bajac tractor in an attempt to obtain all-terrain mobility,[1] towards the end of February 1915.

[3] The Bajac agricultural tractor however proved not mobile enough — the initial experiment had only tested the wire-cutting ability — and had the severe disadvantage of having to approach the enemy lines driving backwards.

Finally, on 9 December 1915 at Souain, on a former battlefield with rough terrain and trenches, and in the presence of General Philippe Pétain, a prototype armoured vehicle motorized with a Baby Holt caterpillar was tested, with provisions to attach Breton's wire cutting apparatus to it.

These very encouraging tests prompted General Estienne to make a formal proposal on 12 December 1915 to build tanks based on a modified, lengthened, Holt caterpillar.