Beetween 1956 and 1958, the Préfecture of Police monitored the activity of Algerian nationalist groups through a binary strategy of information and repression. But in march 1958, the Prefect of Police, Maurice Papon, adopted a new threefold strategy inspired by the tactics of psychological warfare, and aiming to re-conquerer the immigrant population. This strategy included the création of the Auxiliary Police Force (FPA/FAP), voich was founded on 1 december 1959 and recruited among the Arab population. Its establishment, restricted to the Seine region — was the inspiration of captain Raymond Montaner, who proposed the creation of an armed force to counter the special organisation (OS) of the FLN. The first initiative of the FPA was the experimental re-appropriation of FLN's region 1221 - in the 13th district of Paris — so as to disrupt the FLN's financial support and local administration. On 20 march 1960, the FPA occupied the former headquarters of the FLN : militants were arrested, important documents seized and valuable information was obtainedfrom local residents, leading to a series of denunciations. The FPA then sought to infiltrate the district by proselytising in cafés with a largely Muslim clientèle - often were support for Messali Hadj had been Consolidated in the inter-war period. After the success of this experiment, similar initiatives were organised in the 12th and 14th districts of Paris. The FLN reacted to the initial attacks by retraiting and reorganising its forces, and by organising the summary execution of FPA informers. It also sought to discredit the FPA in public opinion through defamatory articles and allégations of torture, an issue that remains controversial. Yet by avril 1960, the local structure of the FLN appeared to have been effectively undemined and there was no armed resistance until October. The involvement of the FPA was thus a turning point in the Battle of Paris, dividing men of the same origin, ail engagea in the construction of an Algerian identity.