There have been several examples of anarchocommunist societies that failed because of external forces, i.e. they were conquered, rather than internal forces.<p>Catalonia in Spain and the Free Territory in Ukraine are the big ones. They lasted for a few years each. Catalonia failed because the Stalinists in Spain betrayed them and that allowed the fascists, backed by Nazi Germany of course to win the civil war. George Orwell fought with the anarchists in Spain. It&#x27;s very enlightening to read about the social institutions they developed before they were defeated militarily.<p>The Free Territory was a model of extreme democracy where power was decentralized to an extremely fine-grained level. It was defeated by the Bolsheviks after Trotsky invited anarchist leaders to a joint meeting and then summarily executed them.<p>Implementing communism does not seem impossible due to internal factors. After a few decades of build-up, both Ukraine and Spain saw the birth of egalitarian communist societies that flourished in the brief time that they were allowed to exist. They were crushed by external authoritarian conquerors.