Columna Durruti
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 -such as George Orwell-), or anarcho-syndicalist groups such as the Durruti Column, the IWA and the CNT.