The Gulag Archipelago by Aleksandr Solzhenitsyn has a lot of stories about how evil the Soviet gulag system was. Below I quote a brief section about Western complicity in Soviet crimes, and about Churchill and Roosevelt in particular.
Context for reading the quote: The "Vlasov army" refers to Russian units in the German army in WWII. They turned against the Germans and saved Prague before the Soviet army arrived. (Soviet histories lie and take credit.) The "act of a loyal ally" refers to the Vlasov army betraying the Germans. And the Soviets routinely punished anyone who'd been taken prisoner by the Germans with 15 years in the gulag (which is preceded by torture). Many other people were executed. One reason is they didn't want people who knew about life in Europe to spread information about it in Russia. The Soviets were so unfairly cruel and murderous it's hard to believe if you haven't read about it. Many people would rather have killed themselves than be executed or tortured and imprisoned by the Soviets. Keep that context in mind when considering turning anyone over to the Soviets.
After saving Prague (bold added):
... the Vlasov army began to retreat toward Bavaria and the Americans. They were pinning all their hopes on the possibility of being useful to the Allies; in this way their years of dangling in the German noose would finally become meaningful. But the Americans greeted them with a wall of armor and forced them to surrender to Soviet hands, as stipulated by the Yalta Conference. In Austria that May, Churchill perpetrated the same sort of "act of a loyal ally," but, out of our accustomed modesty, we did not publicize it. He turned over to the Soviet command the Cossack corps of 90,000 men.
[This surrender was an act of double-dealing consistent with the spirit of traditional English diplomacy. The heart of the matter was that the Cossacks were determined to fight to the death, or to cross the ocean, all the way to Paraguay or Indochina if they had to ... anything rather than surrender alive. Therefore, the English proposed, first, that the Cossacks give up their arms on the pretext of replacing them with standardized weapons. Then the officers—without the enlisted men—were summoned to a supposed conference on the future of the army in the city of Judenburg in the English occupation zone. But the English had secretly turned the city over to the Soviet armies the night before. Forty busloads of officers, all the way from commanders of companies on up to General Krasnov himself, crossed a high viaduct and drove straight down into a semicircle of Black Marias, next to which stood convoy guards with lists in their hands. The road back was blocked by Soviet tanks. The officers didn't even have anything with which to shoot themselves or to stab themselves to death, since their weapons had been taken away. They jumped from the viaduct onto the paving stones below. Immediately afterward, and just as treacherously, the English turned over the rank-and-file soldiers by the trainload—pretending that they were on their way to receive new weapons from their commanders.
In their own countries Roosevelt and Churchill are honored as embodiments of statesmanlike wisdom. To us, in our Russian prison conversations, their consistent shortsightedness and stupidity stood out as astonishingly obvious. How could they, in their decline from 1941 to 1945, fail to secure any guarantees whatever of the independence of Eastern Europe? How could they give away broad regions of Saxony and Thuringia in exchange for the preposterous toy of a four-zone Berlin, their own future Achilles' heel? And what was the military or political sense in their surrendering to destruction at Stalin's hands hundreds of thousands of armed Soviet citizens determined not to surrender? They say it was the price they paid for Stalin's agreeing to enter the war against Japan. With the atom bomb already in their hands, they paid Stalin for not refusing to occupy Manchuria, for strengthening Mao Tse-tung in China, and for giving Kim Il Sung control of half Korea! What bankruptcy of political thought! And when, subsequently, the Russians pushed out Mikolajczyk, when Benes and Masaryk came to their ends, when Berlin was blockaded, and Budapest flamed and fell silent, and Korea went up in smoke, and Britain's Conservatives fled from Suez, could one really believe that those among them with the most accurate memories did not at least recall that episode of the Cossacks?]
Along with them, he also handed over many wagonloads of old people, women, and children who did not want to return to their native Cossack rivers. This great hero, monuments to whom will in time cover all England, ordered that they, too, be surrendered to their deaths.