This organization was formed from the merger of two others, one of which was led by Jules Guesde and Edouard-Marie Vaillant, and until 1914, it was headed by L'Humanite co-founder Jules Jauret, who was assassinated for pursuing a pacifist policy with regard to Germany.
One leader of this organization advocated the idea of "insurrection rather than war" as a counterpoint to the ideas of a similar group at the Congress of Stuttgart. A military conflict involving the country where this organization was located caused it to support a "sacred union" with some of its political opponents. During one of its high points, this organization formed a coalition government with the Popular Republican Movement, but not long after this organization's former leader Daniel Mayer left it to form the Union of Democratic Forces. This organization was formed from the merger of two others, one of which was led by Jules Guesde and Edouard-Marie Vaillant, and until 1914, it was headed by L'Humanite co-founder Jules Jauret, who was assassinated for pursuing a pacifist policy with regard to Germany. For ten points, identify this political organization home to Lionel Jospin and Francois Mitterand, which was the largest component of the Popular Front government of Leon Blum.
One leader of this organization advocated the idea of "insurrection rather than war" as a counterpoint to the ideas of a similar group at the Congress of Stuttgart.
French Socialist Party or Parti Socialiste or French Section of the Workers' International or Section Francaise de l'Iternationale Ouvriere [accept basically anything that indicates that this is the Socialist party of France, since the PS has gone through multiple incarnations, not all of which have been particularly stable]