This chapter discusses four principal types of adaptation of weapons and techniques to a new kind of war: retro-innovation, technological stagnation, the capacity for innovation in wartime, and the invention of completely new weapons. In order to assess the temporal dimension of the relationship between war and technology, with regard to the manufacture of weapons, it is necessary to consider an essential constituent: the human factor. Human intervention appreciably altered the pace of technological adaptation that occurred in response to the demands of the war. It operated on the basis of a threefold temporality including projected future time, real time and confronted time, that intersected with the four forms of adaptation. The use of the steel helmet by the various armies offers a clear example of how the interaction between projected time and retro-innovations functioned, as well as its determining characteristics.