>> in 1937 the communists had murdered many of their own allies (the anarchists) in their own civil war.
George Orwell was nearly killed by the Communists as he had fought with the Anarchists. He had to leave the country incognito and barely escaped with his life. Homage to Catalonia, his book about this time, is a short and highly worthwhile read. Those events certainly helped color 1984.
Orwell left Spain a very disillusioned man; he realized how much propaganda they’d been fed (told of great victories where there had been no batlle at all, and the complete cover-up of disastrous defeats); he’s lucky he got out alive. People like Orwell & Hemingway must have felt like fools as they aged; they’d certainly been played for fools.