From a short book by Christian Hartmann, OPERATION BARBAROSSA. From chapter 3, "The Eve of War."
The Soviet Armed Forces also found themselves in a period of upheaval. By the early 1940s, little remained of their origins in the dramatic years of the Bolshevik Revolution and the Civil War: the political symbolism, perhaps, and the system of having commissars shadow the officers, as well as a few commanders whose careers had begun in 1917. But it was precisely in the officer corps that it was evident how much the Red Army had changed. The officers had been among the first victims of the purges that took place between 1937 and 1940. Of the 5 Marshalls of the Soviet Union, 3 'disappeared', along with 29 of the thirty army commanders and commissars, and 110 of the 195 division commanders. In total, of the 899 highest-ranking officers, 643 were persecuted and 583 killed. In all, about 100,000 ordinary soldiers were subject to some form of repression. This was no coincidence. Although the Workers and Peasants' Red Army, as it was officially called, had been at the disposal of a dictatorship since its inception, it had still been allowed a certain professional autonomy. Now, however, [by summer 1941], the guiding mentality made an abrupt about-turn. Now it was important above all to toe the political line and that meant total orientation on the vozhd, Stalin.