The victory of the revolution in Russia placed in the hands of the revolutionaries the entire mechanism of the most modern, powerful, and skilled political police force that was created over more than fifty years of struggle against the best offspring of a great people. The knowledge of the methods and actions of this police force presents for every fighter an immediate practical importance, because capitalist defense uses the same means everywhere and because all police forces, which are also in solidarity with each other, resemble each other. It is therefore necessary, for a practical purpose, to study well the main instrument of each repression, this machine called the police, which is made to suppress every healthy revolution.