First, it's a misconception that anarchists are against governance. They're against the "state," a hierarchical form of government. They didn't have difficulty

First, it's a misconception that anarchists are against governance. They're against the "state," a hierarchical form of government. They didn't have difficulty organizing for defense/violence--in fact, a common criticism of the Spanish anarchist movement was the appropriation of farm land by force. The failure was due to the coordinated efforts of both capitalist democracies and authoritarian communists to impede their efforts at maintaining their society. Most importantly, IIRC, steel shipments from the US were halted, which reduced their fighting ability.