a reconciliation between the two became obvious by March 1904, since the re-unification envisioned by both the leadership of the SPD and the Free Trade Unions was more along the lines of an integration of the FVdG into the Free Trade Unions. The FVdG's disillusionment with the social democratic movement deepened during the mass strike debate. The role of the general strike for the socialist movement was first discussed within the FVdG in 1901. At the SPD's 1903 congress in Dresden, Raphael Friedeberg proposed discussing the topic, but his proposal was rejected by the congress. The following year, a proposal by Wilhelm Liebknecht and Eduard Bernstein to initiate debate on the topic was accepted, since they had distanced themselves from Friedeberg's positions. Liebknecht and Bernstein, like the left wing of the party, felt the general strike should not be used to provoke the state but rather to defend political rights (especially the right to vote) should the state seek to abolish them. The more conservative faction in the party was opposed to this concept. In 1904, Friedeberg, speaking for the FVdG, advanced the view that the general strike must be a weapon in the hands of the proletariat and would be the last step before the socialist revolution. In 1905, his speech on the topic was even more radical. He claimed that historical materialism, a pillar of Marxism, was to blame for social democracy's alleged powerlessness, and introduced the alternative concept of historical psychism—which held that human psychology was more significant for social development than material conditions. He also recommended the anarchist literature especially Kropotkin's writings rather than Marx's works, which were most influential in the SPD. The position that the general strike could be used, but only as a last resort, became dominant in the party during the mass strike debate. This caused much concern among the conservatives in the party, especially among many trade unionists. At a meeting in February 1906, the trade unionists were placated by party leaders, who said they would attempt to prevent a general strike at all costs. The FVdG reacted by publishing the secret protocols from the meeting in Die Einigkeit, greatly angering the party leadership. At the 1905 party convention, August Bebel, who had always favored a stronger role for the SPD-affiliated unions, proposed a resolution requiring all members of the party to join the centralized trade unions for their respective professions.