By: History.com Editors

1939

Soviet Union invades Poland

Published: November 05, 2009

Last Updated: January 31, 2025

On September 17, 1939, Soviet Foreign Minister Vyacheslav Molotov declares that the Polish government has ceased to exist, as the U.S.S.R. exercises the “fine print” of the Hitler-Stalin Non-aggression pact—the invasion and occupation of eastern Poland.

Hitler’s troops were already wreaking havoc in Poland, having invaded on the first of the month. The Polish army began retreating and regrouping east, near Lvov, in eastern Galicia, attempting to escape relentless German land and air offensives. But Polish troops had jumped from the frying pan into the fire—as Soviet troops began occupying eastern Poland. The Ribbentrop-Molotov Non-aggression Pact, signed in August, had eliminated any hope Poland had of a Russian ally in a war against Germany. Little did Poles know that a secret clause of that pact, the details of which would not become public until 1990, gave the U.S.S.R. the right to mark off for itself a chunk of Poland’s eastern region. The “reason” given was that Russia had to come to the aid of its “blood brothers,” the Ukrainians and Byelorussians, who were trapped in territory that had been illegally annexed by Poland. Now Poland was squeezed from West and East—trapped between two behemoths. Its forces overwhelmed by the mechanized modern German army, Poland had nothing left with which to fight the Soviets.

As Soviet troops broke into Poland, they unexpectedly met up with German troops who had fought their way that far east in a little more than two weeks. The Germans receded when confronted by the Soviets, handing over their Polish prisoners of war. Thousands of Polish troops were taken into captivity; some Poles simply surrendered to the Soviets to avoid being captured by the Germans.

The Soviet Union would wind up with about three-fifths of Poland and 13 million of its people as a result of the invasion.

Timeline

Also on This Day in History

Discover more of the major events, famous births, notable deaths and everything else history-making that happened on September 17th

About the author

History.com Editors

HISTORY.com works with a wide range of writers and editors to create accurate and informative content. All articles are regularly reviewed and updated by the HISTORY.com team. Articles with the “HISTORY.com Editors” byline have been written or edited by the HISTORY.com editors, including Amanda Onion, Missy Sullivan, Matt Mullen and Christian Zapata.

Fact Check

We strive for accuracy and fairness. But if you see something that doesn't look right, click here to contact us! HISTORY reviews and updates its content regularly to ensure it is complete and accurate.

Citation Information

Article title
Soviet Union invades Poland
Website Name
History
Date Accessed
March 27, 2025
Publisher
A&E Television Networks
Last Updated
January 31, 2025
Original Published Date
November 05, 2009

History Every Day

Sign Up for "This Day in History"

Uncover fascinating moments from the past every day! Learn something new with key events in history, from the American Revolution to pop culture, crime and more.

By submitting your information, you agree to receive emails from HISTORY and A+E Global Media. You can opt out at any time. You must be 16 years or older and a resident of the United States.