Even before the liberation of France, the need was felt to explain and justify the action of the BCRA. In late 1944, this task was entrusted to Daniel Cordier, who discharged it under sometimes farcical conditions. Assisted by Vitia and Stéphane Hessel, he soon realised the importance of his work: writing the Livre Blanc du Bureau central de renseignements et d'action.

When the Liberation came, it was vital to be able to identify and list the agents of the Resistance networks, retrace their actions and recognise their rights. It was also essential to check that no enemies, traitors or usurpers could sneak among them and profit from the agents who had demonstrated their commitment to preparing for the future.

One of the great treasures of the special services archives is the collection of cables and telegrams. Conserved at the National Archives and the Defence Historical Service, these documents have their own logic and contain many secrets. They reveal the daily life of the Resistance and make it possible to reconstruct, sometimes with surprising precision, the circuits by which information and decisions were exchanged and thus to improve our understanding of the operations of the Resistance in the field.

Free France produced its own laws, carrying out fundamental legal work that was confirmed following the Liberation and whose traces still remain in today's substantive law. This is the case with ”decree 366”: signed in London on 25 July 1942, this text, which sets the rules by which people can join the Free French Forces, is still valid and continues to have an impact. As for the note on the application of the decree, it gave rise to several particularly moving chirographs.

A recent film, The Imitation Game, recalled the essential role played by the cracking of the Enigma code in the Allied victory. But who knew that the French secret services had recruited Hans Thilo Schmidt as early as 1931? This German spy was the source of the first information about the machine for encrypting secret messages. Without this intelligence, it would probably not have been possible to reconstitute the machine or to figure out how it worked.

The special services of Free France, which have gone down in history under the name of the Bureau central de renseignements et d'action (BCRA, Central Bureau of Intelligence and Operations), were founded in London on 1 July 1940. However, many months would pass before Colonel Passy's services were fully operational. They gradually widened the scope of their operations and learned to work with the British.

Long known as the ”Bureau central de renseignements et d'action collection”, the archives of the French special services during the Second World War arrived at the Château de Vincennes following long tribulations, passing from hand to hand and from one shore to the other of the Channel and the Mediterranean. Finally donated to the Army Historical Service by the Directorate General of External Security in December 1999, and undergoing classification work since 2013, the archives had actually been deposited in secure premises in Vincennes for longer than that.

From the BCRA to the DGSE, from yesterday to today… The French intelligence services have successfully evolved to adapt to new missions. While this has meant reforming the organisations to keep them efficient, the principles that guide them have remained intact. Subject to political power, the intelligence services have seen their capacities evolve to ensure they can carry out their missions and face an ever-changing sequence of threats. The organisational principles and strategic choices are still there, but the resources deployed and the missions themselves have changed. Evolutions in France's geopolitical context and the challenges it faces, the decolonisation process, the end of the Cold War, technological revolutions and the development of terrorist threats have led the Service to keep changing in response to security needs. At the same time, the choice to conserve a single, integrated structure has been constantly confirmed, and continues to offer France a high level of clandestine obstruction and operation.