What did Josef Stalin do to help win war against Germany during world war two?

Despite doing some things detrimental to military preparedness, like purging good officers, and adopting a poor initial deployment in 1941, Stalin deserves enormous credit for the defeat of nazi Germany. It was Stalin that industrialized the USSR and built up enormous armies--far exceeding German estimates--prior to the nazi attack. The bulk of German fighting power was committed to the war against the USSR; even after D-day, the Germans still devoted over 60% of their forces to the eastern front. And those forces were progressively worn down in massive battles from 1941-45. It was said that the western allies destroyed a total of 154 German divisions in the war but the soviets destroyed 367.