In the Spanish Civil War, international volunteers fought on the side of the Republicans.
Republican side is one of the names given by contemporary historiography to the Spanish military and political organizations that, after the partial defeat of the coup d'état of July 1936, defended the Republic during the Spanish Civil War -which ended in 1939-, confronting to the Nationalist side.
The Republican side sought various ends depending on the faction, from the maintenance of multiparty parliamentary democracy by the republican parties to the establishment of a socialist state by communists and socialists, or a libertarian social revolution on the part of the anarchists, therefore in the Republican side there were diverse political ideologies that united to fight the insurgents.
Although hardly received external support from the allied powers of the Second World War, the support of what were called the Voluntary International Brigades was notorious.