After the military uprising failed in Barcelona in July 1936, CNT and UGT unions took over many Catalan firms and, with militia columns, collectivised farms in eastern Aragon. The Generalitat regulated industrial collectivisation in October 1936; it was curtailed after May 1937.
The failure of the 19 July 1936 coup left Republican authority weak in Catalonia, and union and revolutionary committees took over firms, services and land. The Generalitat's Decree on Collectivisations and Workers' Control (24 October 1936) was a compromise: firms with over 100 workers, or abandoned ones, were collectivised and run by councils elected by workers' assemblies; firms of 50-100 workers could collectivise by a two-thirds vote; smaller firms stayed with owners under worker supervision. In Aragon an anarchist-dominated Defence Council coordinated collectives from October 1936. Historians differ on how voluntary, efficient and widespread the collectives were, and on how much war, rather than collectivisation, explains economic difficulties.
Collectivised firms and farms operated in Republican territory for up to about two and a half years. Catalan industrial output fell to 55 (early 1936 = 100) by April 1938 amid war conversion, shortages and inflation; collectivisation was only one factor.
After the May 1937 clashes in Barcelona the CNT lost ground. A decree of 11 August 1937 dissolved the Aragon Defence Council and Líster's 11th Division dissolved many collectives; the Generalitat could nationalise firms from November 1937. The Aragon front collapsed in March 1938 and the war ended in 1939.
The Generalitat's decree of 24 October 1936 compulsorily collectivised firms with over 100 workers and abandoned firms under elected company councils, allowed 50-100 worker firms to collectivise by two-thirds vote, and left smaller firms with owners under worker supervision.[1]
Historians differ over how voluntary and productive the rural collectives were: Seidman finds participation was part spontaneous and part coerced and that internal divisions compounded war and political hostility; Balcells cautions that propagandists on both sides distorted the record.[1][2][3]
Collectivisation covered a minority of Republican-zone land (Seidman cites 18.5%), and Catalan industrial output fell from 100 in early 1936 to 70 by February 1937 and 55 by April 1938, amid war conversion, shortages and inflation, so collectivisation's own effect is hard to isolate.[1][2]