Well, here's a book by George Orwell I should definitely read, all about the Spanish Civil war; the socialists, the communists, the fascists, the anarcho-syndicalists et al. The birth and death of political idealism...looks like powerful stuff. If I ever get around to reading it that is ;-)
Orwell served as a private in the Spanish civil war and it was these experiences that inspired his later books Animal Farm and 1984. Here's a quote, what's perhaps surprising is how relevant it still is today:
"He had learned a hard lesson,especially about the new political Europe. Totalitarianism, the new creed of 'the streamlined men' of Fascism and Communism, was a new manifestation of Orwell's old Catholic enemy, the doctrine of Absolutism"  - "the ghost of Torquemada had arisen, imprisonment without trial, confessions extracted under torture with summary executions to follow."  "The essential fact about a totalitarian regime is that it has no laws. People are not punished for specific offences, but because they are considered to be politically or intellectually undesirable. What they have done or not done is irrelevant."