Socialist Party of France

(SPF; Parti socialiste de France), a party founded in the early 20th century through the unification of a number of socialist organizations opposed to Millerandism. The first step toward the formation of the SPF was taken in 1901, when the Workers’ Party, the Social Revolutionary Party (the Blanquists), and the Communist Alliance (a group that had split from the Allemanists and joined the Blanquists) united in a single organization, the Revolutionary Socialist Union. The party developed its basic structure at a conference in Ivry-sur-Seine in November 1901, a congress in Commentry in September 1902, and, finally, at a congress in Reims in September 1903, at which it was named the Socialist Party of France.

The leaders of the party were J. Guesde, P. Lafargue, and E. M. Vaillant. The Guesdistes constituted the basic core of the SPF, which had more than 17,000 members in April 1905. The party was strongest in the industrial departments—Nord, Pas-de-Calais, Seine, Oise, and Aube. Reflecting a trend to unite the country’s socialists, Guesde introduced a resolution at the Sixth Congress of the Second International, held in Amsterdam in August 1904, which led to the unification of the SPF and the French Socialist Party and several other parties in April 1905 into a single socialist party.