On April 3, 1922 Stalin became the first General Secretary of the Communist Party of the Soviet Union. Following Lenin's death in 1924, Stalin consolidated his power and implemented a centralized command economy, industrialization and collectivization, which rapidly expanded Russia's industrialization. He disrupted food production to such an extent that it contributed to the Ukraine famine of 1932–33. Stalin conducted the "Great Purge" from 1934 to 1939, to eliminate those he deemed so-called "enemies of the working class". Hundreds of thousands of senior and military officers were interned in prison camps, exiled, or executed. In August 1939 the Soviet Union signed the Molotov-Ribbentrop Pact, a non-aggression pact negotiated by Soviet foreign minister Vyacheslav Molotov and German foreign minister Joachim von Ribbentrop. It also contained a secret protocol regarding the invasion and partition of Poland. On September 1, 1939, Germany invaded Poland from the west, and on September 17, the Red Army invaded the eastern part of Poland. In a series of four mass deportations, Russia deported up to one million Polish men, women and children as prisoners to farthest reaches of Russian territory. In April of 1940, the Germans discovered mass graves near Smolensk, Russia. They were the bodies of 16,000 Polish officers that were executed by the Soviet NKVD, upon the signed order of Stalin and Lavrentiy Beria. Stalin denied responsibility
Hitler gave a top secret directive to the military code-named Fall Weiss (Case White) ordering the preparation of military operations against Poland for from September 1 forward. The plan originated in 1928 by Günther Blumentritt and Erich von Manstein while the two were serving as staff officers under General Gerd von Rundstedt with Army Group South in Silesia.
Buchenwald Evacuation: As US forces approached the camp, the Nazi Germans began to evacuate over 28,000 Jewish prisoners from the main camp and an additional several thousand prisoners from the subcamps of Buchenwald. About a third of these prisoners died from exhaustion en route or shortly after arrival, or were shot by the SS. The underground resistance organization in Buchenwald, whose members held key administrative posts in the camp, saved many lives. They obstructed Nazi orders and delayed the evacuation.