Partit Castala Proletari
The Partit Catala Proletari was a left-wing political party in Catalonia. In July 1936 its leaders agreed to join with the Socialist Party (PSOE) and the Communist Party (PCE) to form the Partit Socialista Unificad de Catalunya (PSUC). Members also came from the Union General de Trabajadores (UGT). Juan Comorera was elected general secretary of the PSUC. By the middle of 1937 the PSUC claimed to have a membership of 50,000.
Primary Sources
(1) Sam Russell, Heroic Voices of the Spanish Civil War (2009)
I didn't have more than about three weeks' training near Albacete. That was in early November 1936, when we were told that we were going to Madrid. We were taken down in trucks to Albacete, put on trains there and went up to the front with the French Battalion. We didn't see really anything of Madrid right away, we arrived there during the night. We actually went into action on 6 or 7 November 1936. By the time we got out it was light and we marched through the streets. People gathered around and at first thought we were Russians, but they soon realized that we were not. There was a tremendous reception because the word went round. While we were getting out of the trains and forming up, the crowd gathered and cheered us. We didn't realize immediately how serious the military situation was and how close to Madrid the fascists had got. We were taken into University City, that was the first encounter.