International Brigades
The headquarters of the brigade was located at the Gran Hotel, Albacete, Castilla-La Mancha. They participated in the battles of Madrid, Jarama, Guadalajara, Brunete, Belchite, Teruel, Aragon and the Ebro. Most of these ended in defeat. For the last year of its existence, the International Brigades were integrated into the Spanish Republican Army as part of the Spanish Foreign Legion. The organisation was dissolved on 23 September 1938 by Spanish Prime Minister Juan Negrín in a vain attempt to get more support from the liberal democracies on the Non-Intervention Committee.
The International Brigades were strongly supported by the Comintern and represented the Soviet Union's commitment to assisting the Spanish Republic (with arms, logistics, military advisers and the NKVD), just as Portugal, Fascist Italy, and Nazi Germany were assisting the opposing Nationalist insurgency. The largest number of volunteers came from France (where the French Communist Party had many members) and communist exiles from Italy and Germany. Many Jews were part of the brigades, being particularly numerous within the volunteers coming from the United States, Poland, France, England and Argentina.
Republican volunteers who were opposed to Stalinism did not join the Brigades but instead enlisted in the separate Popular Front, the POUM (formed from Trotskyist, Bukharinist, and other anti-Stalinist groups, which did not separate Spaniards and foreign volunteers), or anarcho-syndicalist groups such as the Durruti Column, the IWA, and the CNT. Provided by Wikipedia