Soviet invasion of Poland

The Soviet invasion of Poland was a military conflict started by the Soviet Union without officially declaring war. It happened on 17 September 1939, sixteen days after Nazi Germany had invaded Poland from the west. This invasion lasted for twenty days and ended on 6 October 1939. By that time, Nazi Germany and the Soviet Union had divided and taken over all of Poland’s land, which is sometimes called the Fourth Partition of Poland.

The invasion was planned in secret as part of an agreement called the Molotov–Ribbentrop Pact, signed on 23 August 1939, between Germany and the Soviet Union. This agreement secretly decided which parts of Poland each country would control. The Red Army had many more soldiers than the Polish defenders and faced only small resistance.

After the invasion, the Soviet Union began controlling the eastern part of Poland. Many Polish people were taken away to faraway places, and some leaders were arrested or removed. The Soviet forces stayed in eastern Poland until 1941 when Germany broke its agreement and attacked the Soviet Union. After World War II ended, the borders between Poland and the Soviet Union were officially set in 1945.

Prelude

In early 1939, the Soviet Union started talks with the United Kingdom and France to work together against Nazi Germany, which was building up its military under Adolf Hitler.

Joseph Stalin then made a deal called the Molotov–Ribbentrop Pact with Hitler on August 23, 1939. This non-aggression pact secretly agreed to split parts of Europe between Germany and the Soviet Union if there was a war. One week later, on September 1, 1939, Germany invaded Poland from the west, north, and south. Polish forces moved toward the southeast, hoping for help from France and Britain, but no help arrived.

On September 17, 1939, the Soviet Red Army entered areas in eastern Poland called the Kresy, as planned in the secret agreement. Some Polish cities let the Soviet troops in, thinking they were there to fight Germany. The Soviet government said they were acting to protect Ukrainians and Belarusians living in eastern Poland, claiming Poland could no longer keep them safe. With battles happening on two sides, Poland decided it could no longer defend its position and told its troops to leave for neutral Romania.

Poland between the two world wars

The League of Nations and peace treaties from 1919 did not help bring peace in Europe. Strong feelings and anger in countries like Germany, Austria, and Hungary led to big disagreements and desires for more land. Poland tried to grow bigger, hoping to create a group of countries that could stand up to big powers like Russia or Germany.

In 1920, after a big fight called the Polish-Soviet War, Poland and Soviet Russia agreed on a peace treaty. This treaty decided the borders between them. Later, most countries agreed with Poland's eastern borders in 1923.

Further information: Molotov–Ribbentrop Pact, German–Soviet Credit Agreement (1939), and Anglo-Polish alliance

When Germany took over Prague in March 1939, talks began between the Soviet Union, Britain, and France to protect against German attacks. However, Poland was not part of these talks. The Soviet Union did not trust Britain and France, thinking they would not help if Germany attacked. Poland refused to let Soviet troops enter its land, fearing they might not leave. Meanwhile, Germany and the Soviet Union secretly talked about working together.

By August 1939, Germany and the Soviet Union signed an agreement to work together economically. Soon after, they signed the Molotov–Ribbentrop Pact, secretly planning to divide Poland between them. The next day, Britain and Poland signed an agreement to protect Poland’s independence.

German invasion of Poland and Soviet preparations

Before the war began, Germany tried to stop Britain and France from getting involved. Germany made some demands to Poland, like giving up a city called Danzig (Gdańsk) and holding a vote in an area called the Polish Corridor. But Poland did not agree to these demands.

On September 1, 1939, Germany started its attack on Poland. German forces moved into Poland from the west. At the same time, the Soviet Union began getting its army ready. The Soviet Union wanted to join the fight but waited for the right moment. They needed more time to prepare their troops.

On September 17, 1939, the Soviet Union announced that Poland’s government had stopped working. The Soviet Army then moved into Poland from the east. They said they were protecting people in parts of Poland. This was part of a plan between Germany and the Soviet Union to divide Poland between them.

Soviet invasion of Poland

Before invasion

On the morning of 17 September 1939, Poland’s eastern areas were still mostly under Polish control. Polish forces were focused on fighting in the south and central areas, like Tomaszów Lubelski, Zamość, Lwów, Warsaw, Modlin, and along the Bzura river. Rail lines were still working, and some factories were still making planes. Cities like Warsaw, Lwów, Wilno, Grodno, Łuck, Tarnopol, and Lublin were still held by Polish troops.

Opposing forces

A large Soviet force of around 450,000 to 1,000,000 troops entered eastern Poland from two directions. Marshal Semyon Timoshenko led the Ukrainian Front, and General Mikhail Kovalyov led the Belarusian Front. Poland had expected the Soviet Union to stay neutral, so they had only a small force defending the eastern border.

Military campaign

On 17 September at 4:00 a.m., the Polish commander ordered troops to fall back and only fight Soviet forces if attacked. Because of damaged communication systems, some Polish units still fought Soviet troops. The Polish government decided to leave Poland and reorganize in France. Over the next few weeks, Soviet and German troops met and sometimes worked together. Cities like Lwów, Wilno, and Grodno were taken by Soviet forces. The last Polish troops surrendered on 6 October, ending the fighting.

Domestic reaction

Some Ukrainians, Belarusians, and Jews in eastern Poland welcomed the Soviet troops. Local Communists held welcome events, giving bread and salt to the soldiers.

International reaction

Britain and France did not strongly oppose the Soviet invasion. Britain had promised to help Poland if Germany attacked, but not if the Soviet Union did. France had also made promises to Poland but did not act. Some British leaders thought the Soviet actions were reasonable, while others were upset. Winston Churchill spoke about the need to stop German plans in the region.

Aftermath

Main article: Occupation of Poland (1939–1945)

Further information: History of Poland (1939–1945) and Polish prisoners of war in the Soviet Union after 1939

In October 1939, the Soviet Union told its people that their soldiers had lost about 737 and around 1,862 were hurt during their time in Poland. Polish experts thought the numbers were much higher. On the Polish side, between 3,000 and 7,000 soldiers died fighting, and many more were captured.

The Soviet Union did not recognize Poland as a country when they invaded. Neither side officially declared war. This decision later caused criticism. During this time, many Polish prisoners of war were sadly killed by Soviet forces.

On September 28, 1939, the Soviet Union and Germany signed a treaty. This treaty changed the borders, giving the Soviet Union control over land with about 13.5 million Polish people. The Soviet leaders told people they were coming to help Poland from the Germans, but this was not true. They took over private property and made many arrests.

The Poles and Soviets restarted talks in 1941 but stopped again in 1943.

The areas taken by the Soviet Union had many different people living there, including Poles, Ukrainians, Belarusians, Jews, Russians, and Germans. The Soviet Union changed these areas to fit their way of governing, which caused many problems for the local people. These changes helped shape the future of Ukraine and Belarus.

In communist and Russian propaganda

During the time when communism ruled, leaders in the Soviet Union called the invasion of Poland a "liberation campaign." They used this term in all their official talks and writings. Even after secret agreements from 1939 became known in the west, the Soviet Union kept saying these papers did not exist until 1989. True history about what happened could only be studied after the Soviet Union ended. Before that, it was hard to learn the real story because of strict rules and closed records.

In Russia, opinions about this event have changed over time. Some leaders have called the agreement that led to the invasion "immoral," while others have praised it for helping protect the Soviet Union. Even today, some in Russia still describe the invasion as a "liberation" for people in certain areas.