German and Soviet Rocketeers
From Mike's Blazing the Trail (p. 275):
[During World War II, leading German rocketeer] Wernher von Braun was arrested and spent two weeks in a prison in an internal strife among the rival factions of the Nazi Germany. Two other Peenemünde rocketeers, Klaus Riedel and Helmut Gröttrup, were arrested at the same time and later also released. Von Braun's troubles, however, did not come even close to the sufferings of the Soviet rocketeers. Many Soviet scientists and engineers, though absolutely loyal to the Soviet State, enthusiastic about the socialist paradise they were building, and devout Communist Party members themselves who had earlier, in the 1920s and early 1930s, cheerfully approved the extermination of millions of the “enemies of state” were now themselves arrested, tortured, murdered, imprisoned, and banished, after token trials or by executive order. The fate of these specialists was not any different from that of many millions of others, annihilated by that time by the enthusiastic socialist state (being aided, abetted, and admired, one should add, by numerous leftists in the West). Many of those who survived the ordeal carried the fear through the rest of their lives, instilling slavish attitudes to the following generations of their children and grandchildren. Notably, some even preserved the cherished belief in the socialist ideas as the highest achievement of the human race.
A number of rocketeers and space enthusiasts perished on march to the socialist paradise, especially in the Soviet Union and the People's Republic of China. (See M. Gruntman, Blazing the Trail, AIAA, 2004 for the historical and technological context.) They were arrested, tortured, and sent to concentration labor camps where excessive hard work, savage living conditions, starvation, and abuse by guards took a tremendous toll.
Pages 273-275 in Blazing the Trail describe what happened to a few leading Soviet rocketeers.
Page 444 in Blazing the Trail describes some relevant events in the Communist China.
These millions of innocent people were annihilated by social engineers of enthusiastic socialist states, who were being aided, abetted, and admired by numerous leftists in the West. Without this help of the leftists, the human cost of Communism would have been much smaller and the forces of freedom would have won the Cold War much sooner, finishing off the Communist ideology.