The violent police repression of the Algerian demonstration of 17 October 1961 has given rise to considerable political and historical debate. Through the use of previously unseen police and intelligence reports, as well as a large volume of captured internal FLN documents available in the Archives of the Paris Préfecture de Police, a new insight is provided into the clandestine structure of the FLN fédération de France during 1961 and how and why the demonstration was planned. The article discloses the existence of a previously unknown, centralized Federal structure based in Paris and how this body liaised, via a network of porteurs de valises, with the Federal Committee in Germany. It is argued that the demonstration was organized against the wishes of the Gouvernement provisoire de la République algérienne, as part of a gambit for pre-independence power. The fédération leadership, disappointed by previous lack of support from the French left, did not seek PCF and wider left participation in the demonstrations : this decision left the Algerian demonstrators more exposed to police repression.