In the military sector, the "knowledge reinforces power" adage depends on the capacity of the military to appropriate and hence protect scientific and technical knowledge. Because they imply that the content of inventions should be divulged, industrial property rights are not suited to the military research sector. This is why, early in history, secrecy has played the role of mediator in the relationship between science and war. The 20th century saw the concept of military secrecy enshrined in law, and the number of inventions mandated to remain secret has grown. During the Cold War, the firewalls erected between the civil and military sectors were used to explain the loss of competitiveness of some national economies. Today, the current convergence of the civil and military sectors can be seen as an opportunity to extend the concept of military defense secrecy concept beyond the military sector and to include the entire national research effort, which is always potentially war research, as explained by J.D. Bernal in 1936. Combined with the introduction of market rules into the operation and management of national research, this growing role of secrecy could lead to a slowing down of technical progress and to a misallocation of resources.