There was no meaningful opposition to Stalin left at the start of the war.
The purges meant that loyalty to Stalin was the only important consideration in political advancement and power.
Stalin therefore had the authority to impose his will on everyone around him.
This was a strength for the Soviet Union when it came to the conduct of the Second World War.
The cult of personality built up around Stalin was very effective in securing the loyalty and devotion of a large proportion of the Soviet people.
In a time of rapid economic transformation and personal insecurity during the purges, many Russians held onto the figure of Stalin as the man to bring about improvements.
Mistakes and excesses tended to be blamed on others such as Yezhov for the Great Purges.
The propaganda of the late 1930s had focused on Stalin's cult of personality and an increasing nationalist and patriotic feeling.
This helped during the war years as the Soviet people readily adapted to the demands of the war.