From Churchill and Orwell: The Fight for Freedom, by Thomas E. Ricks (Penguin, 2017), Kindle Loc. 1153-70, 1262-68:
On the afternoon of May 7, some six thousand additional government troops arrived, and the fighting ended. Again, Orwell was impressed by how well these rear-area units were equipped, compared with his front-line unit. To his disgust, the government blamed all the fighting on POUM, because it was the weakest of the leftist factions.
Watching all this, Orwell arrived at some conclusions that clashed with leftist conventions of the era. At a time when leftist solidarity was considered mandatory, the right thing to do, Orwell began to harbor suspicions. Observing the fighting in Barcelona between different antifascist factions, he noted, “You had all the while a hateful feeling that someone hitherto your friend might be denouncing you to the secret police.”
In effect, the events in Barcelona forced him to examine the left as he once earlier had scrutinized imperialism and capitalism. He concluded, “The Communist Party, with Soviet Russia, had thrown its weight against the revolution.” It was determined to systematically wipe out the anticommunist parts of the left—first POUM, then the anarchists, and then socialists.
But to say this in public was a form of modern heresy. Orwell realized, with shock, that the left-wing newspapers did not report the situation accurately, and did not want to. Rather, they willingly accepted lies. “One of the dreariest effects of this war has been to teach me that the Left-wing press is every bit as spurious and dishonest as that of the Right,” he wrote. This set him on his life’s work, to push continually to establish the facts, no matter how difficult or unpopular that might be.
On May 10, 1937, he left Barcelona to return to the front, where the POUM was still deployed, despite being suppressed back in Barcelona by the government whose territory it was defending. On May 11, the POUM was denounced in the Daily Worker as “Franco’s Fifth Column.” Posters appeared on Barcelona walls with the headline TEAR THE MASK, showing a face marked POUM, and a fascist face underneath it. It was classic “big lie” propaganda.
The POUM soldiers at the front there had not been told that they were being denounced in Barcelona, and the newspapers from the city remained quiet about the purge.
From Spain on, his mission was to write the facts as he saw them, no matter where that took him, and to be skeptical of everything he read, especially when it came from or comforted those wielding power. This became his faith. “In Spain, for the first time, I saw newspaper reports which did not bear any relation to the facts,” he wrote a few years later. He continued:
I saw great battles reported where there had been no fighting, and complete silence where hundreds of men had been killed. I saw troops who had fought bravely denounced as cowards and traitors, and others who had never seen a shot fired hailed as the heroes of imaginary victories; and I saw newspapers in London retailing those lies and eager intellectuals building superstructures over events that had never happened. I saw, in fact, history being written not in terms of what happened but of what ought to have happened according to various “party lines.”