Who devised the blitzkrieg theory that Germany applied?

Fuller focused his attention on the potential of new weapons, especially tanks and aircraft. He worked with his colleague B. H. Liddell Hart on developing ideas for the mechanisation of armies and, together with him, launched a campaign in favour of mechanising and modernising the British Army. In his approach, areas of heavy enemy activity were to be avoided so that they could eventually be encircled and destroyed. He is regarded as one of the progenitors of Blitzkrieg. Heinz Guderian paid out of his own pocket for the translation of his manual Provisional Instructions for Tank and Armoured Car Training.

Liddell Hart argued that infantry should be carried alongside fast-moving armoured formations, troops he referred to as "tank marines". He himself pointed out that the German Wehrmacht adopted theories developed from those of J. F. C. Fuller and from his own.

After the war, Liddell Hart himself tried to pin down his influence on the way the German generals fought. The influence attributed to him at that point had not been claimed before, and no contemporary, pre-war documentation has been found to support it. He has been criticised for having created the concept of a Blitzkrieg doctrine after the fact, rather than influencing its original development. What is on record is that, in the 1930s, the German army put into practice tactics similar in many respects to Fuller's analysis, which came to be known as Blitzkrieg.