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The Soviets were caught by surprise and suffered massive casualties as a result. See this Wikipedia article. Lots of aircraft were destroyed on the ground, not the air. The first attacks began at 03:00 on 22 June. The Soviets had been caught by surprise, their aircraft bunched together in neat rows which were vulnerable. The results were devastating ... ...


18

The Wikipedia article cited in another answer lists among reasons ...equipment, like that of the Red Army, was largely obsolescent and suffering from prolonged use. The Great Purges had also hit aircraft manufacturers, and the loss of personnel ended the Soviet lead in aircraft design and aeronautics (...) The aviation industry was disrupted, ...


15

Magnus Hirschfeld, a researcher on sexuality and early advocates for gay rights amassed a huge body of research on homosexuality and transsexuality. In '33, he was heading and institute at the Charité University in Berlin. The Archive of his Institute was burned completely, a huge body of research was lost. This did not happen "just" because he was jewish, ...


14

Organizational deficiencies, technical obsolescence, inexperience of pilots, surprise caused by Stalin's blunder First of all, claims that VSS lost 4000 planes in the first three days of war is somewhat dubious. This is mostly based on German sources, which is understandable since Soviets usually omitted exact data from this embarrassing period . Only ...


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Heinrich Georg Stahmer Nazi Diplomat to China. (src ullsteinbild: 00253012, 00294136, 00294144)


6

A vast majority of success of Blitzkrieg hinged on surprise factor which was available only in the earlier stages of war: https://www.britannica.com/topic/blitzkrieg Blitzkrieg, (German: “lightning war”) military tactic calculated to create psychological shock and resultant disorganization in enemy forces through the employment of surprise, speed, ...


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