By Guderian's account he single-handedly created the German tactical and operational methodology. Between 1922 and 1928 Guderian wrote a number of articles concerning military movement. As the ideas of making use of the combustible engine in a protected encasement to bring mobility back to warfare developed in the German army, Guderian was a leading proponent of the formations that would be used for this purpose. He was later asked to write an explanatory book, which was titled "Achtung Panzer!" (1937). In it he explained the theories of the tank men and defended them.