The anarchists have always been such a problem that even the Communists didn’t trust them. They used them as a sort of spearhead, because the anarchists were crazy enough to do anything, but then they eliminated them.
During the Spanish Civil War, the anarchists and the communists, including the Russians sent by Stalin, were theoretically on the same side. But as soon as they took over an area, the first people the Communists shot were the anarchists, even before such dangerous people as the local parish priest, the nun who taught primary school, or somebody who wrote for a conservative paper.
That’s true; the communists knew that anarchists opposed to government didn’t want to be governed by communists either, so they killed them off. By 1937 their leader was dead and morale was at rock-bottom. The anarchists who had seized Barcelona gave it up without a fight later in the war.