Analyzing the development of the German and British air forces between the world wars reveals the importance of crafting strategy, identifying associated requirements, and marshaling the required resources to turn requirements into capabilities. Factors beyond the state’s control often drive technological requirements. Structural factors demanding innovative responses include the technological progress of potential enemies and of civil society, as well as shifts in the state’s own geopolitical circumstances. Yet the task of responding to these structural factors—of translating the state’s desired security ends into military technological means—requires an intentional, collaborative, human effort. The development of specific airpower capabilities in Germany and Britain during the interwar years illustrates the role of strategic innovators as “system builders” and doctrine entrepreneurs who brave the gauntlets of government bureaucracy, industry, and academia to turn theory into capabilities.