A pre-world war purge of all competent top brass.
It’s a tradition, Stalin did it before WWII.
And this little purge ultimately cost the lives of AT LEAST 150,000 Sov soldiers, perhaps even treble that, due to the incompetent generalship remaining. Not unlike Shcharkovsky in WWI, except (shall we say) involuntary.
Not that I weep for this development, mind you, but pls lay the finger of blame where it belongs, namely, Stalin getting conned by Hitler's minions.