Soviet Intervention & Partition of Poland
Hastening to end the war before the Western powers could act, the Germans on September 3 requested the Soviet Union to move against Poland, but the Russians were not ready. The German speed had taken them by surprise. After the German ambassador in Moscow submitted a second request on September 10, the Soviet government apparently became concerned lest the war end before it could enter it and the Germans refuse to honor the secret protocol and evacuate the territory east of the demarcation line.
On September 17, two Soviet army groups, the White Russian Front in the north and the Ukrainian Front in the south, each with two armies, marched into Poland. They met little Polish resistance and concentrated their efforts on shepherding the Germans out of the Soviet zone. A last-minute German attempt to secure control of the oilfield south of Lwow in the Soviet zone had aroused suspicion. Approximately 217,000 Polish troops fell prisoner to the Russians. Many of them survived to fight Germany again either in the west or in Soviet service, but some thousands, mostly officers, found their graves in Katyn Forest.
In formulating the secret protocol to the nonaggression treaty, both Germany and the Soviet Union had assumed that a truncated independent Polish state would be allowed to survive. On September 25, however, having made a hint to this effect. six days earlier, Stalin proposed that the conquerors divide Poland between them.
In Moscow, on September 28, Ribbentrop signed a Soviet-German treaty of friendship. A secret protocol revised the demarcation line. Germany received the Province of Lublin and the Province of Warszawa eastward to the Bug River, and as compensation the USSR included Lithuania in its sphere of influence. The Soviet Union also agreed to deliver to Germany 300,000 tons of crude oil annually, the estimated output of the Polish fields. The revision placed the Soviet border approximately on the Curzon Line (q.v.) and gave Germany nearly all of the ethnically Polish territory.
On the same day, Ribbentrop and Molotov issued a statement claiming that the settlement had created a basis for a lasting peace in eastern Europe and calling for an end to the war between Germany and the Western powers.