Introduction
The Invasion of Poland, which began on September 1, 1939, marked the formal outbreak of World War II in Europe. It was a military campaign that had global repercussions, ultimately leading to a conflict that engulfed much of the world over the next six years. The invasion involved Nazi Germany attacking Poland from the west, later followed by a Soviet invasion from the east on September 17, 1939, in accordance with a secret clause in the Molotov–Ribbentrop Pact. This event signaled the failure of appeasement, the collapse of interwar diplomacy, and the beginning of one of the deadliest conflicts in human history.
Historical Context
The interwar period between 1918 and 1939 was marked by growing tensions in Europe. The Treaty of Versailles (1919), which ended World War I, placed harsh penalties on Germany, including territorial losses and severe economic reparations. The treaty also created several new nations, including a resurrected Poland, which had not existed as an independent state for over a century, having been partitioned by Prussia, Russia, and Austria in the late 18th century.
The Second Polish Republic, established in 1918, was ethnically diverse, housing large Ukrainian, Belarusian, Jewish, and German minorities. Poland’s borders were contested, and its foreign policy aimed at balancing relations with its two powerful neighbors—Germany and the Soviet Union. The Polish–Soviet War (1919–1921) and the resulting Treaty of Riga pushed Soviet Russia’s borders eastward, creating resentment in the Soviet Union.
Meanwhile, Adolf Hitler, who rose to power in 1933, was determined to overturn the Versailles Treaty, expand German territory (Lebensraum), and dominate Eastern Europe. The German annexation of Austria (Anschluss) in 1938 and the occupation of Czechoslovakia in 1938–1939 showcased Hitler’s expansionist agenda. Western powers followed a policy of appeasement, hoping to avoid another large-scale war. However, Hitler’s eyes soon turned to Poland.
The Molotov–Ribbentrop Pact
One of the most pivotal diplomatic developments before the invasion was the Molotov–Ribbentrop Pact, a non-aggression treaty signed between Nazi Germany and the Soviet Union on August 23, 1939. Officially, it promised that neither side would attack the other. Secretly, however, it included a protocol dividing Eastern Europe into German and Soviet spheres of influence.
Under this secret agreement:
- Germany would occupy western Poland.
- The Soviet Union would claim eastern Poland, as well as the Baltic states and Finland.
This pact gave Hitler the confidence to invade Poland without fear of Soviet intervention. It also ensured the Soviet Union would benefit territorially from the war’s initial phase.
The German Invasion
On September 1, 1939, Germany launched “Fall Weiss” (Case White), a massive surprise attack on Poland. The German assault was characterized by Blitzkrieg tactics—a swift, coordinated military strategy involving fast-moving mechanized infantry, tanks, and air support.
Germany attacked from:
- The north (from East Prussia),
- The west (from Germany proper),
- The south (from Slovakia, then a German client state).
The Luftwaffe (German air force) bombed Polish cities, railroads, and communication lines. Polish defenses, though courageous and determined, were overwhelmed by superior numbers, better equipment, and tactical surprise. The Polish army was not fully mobilized, and Poland’s terrain allowed the Germans to exploit gaps in their defensive lines.
The Soviet Invasion
On September 17, 1939, the Red Army invaded eastern Poland, citing the collapse of the Polish state and the need to protect ethnic Ukrainians and Belarusians. This was in direct accordance with the Molotov–Ribbentrop Pact’s secret protocols.
The Polish government, already retreating toward Romania, found itself caught between two powerful invaders. Facing encirclement and defeat, it ordered its forces to avoid direct conflict with the Soviets and continue fighting the Germans. However, some Polish units did engage the Red Army, particularly in the east.
The Soviet invasion sealed Poland’s fate. On September 28, Warsaw surrendered, and by early October, all of Poland was occupied.
International Response
On September 3, 1939, Britain and France declared war on Germany, honoring their mutual defense pact with Poland. However, they did not launch a direct military offensive in the west, leading to what became known as the Phoney War or “Sitzkrieg”—a period of inactivity on the Western Front.
While both Western powers sent aid and expressed support for the Polish cause, they were unprepared for immediate military engagement with Germany. This lack of action was demoralizing to the Poles and contributed to their rapid defeat.
Division and Occupation
After the invasion, Poland was divided roughly along the Bug River:
- The Germans controlled the western and central regions, including Warsaw and Kraków.
- The Soviets controlled the eastern territories, which included much of modern-day western Ukraine and Belarus.
Under German occupation:
- The General Government was established as a colonial administration.
- Polish elites, clergy, intellectuals, and Jews were targeted for execution or deportation.
- The Nazi campaign of terror included mass shootings, the construction of ghettos, and, eventually, the creation of death camps such as Auschwitz and Treblinka.
Under Soviet occupation:
- The NKVD (Soviet secret police) arrested tens of thousands of Polish officers, officials, and intelligentsia.
- The Katyn Massacre (1940), in which over 20,000 Polish officers and intellectuals were executed by the Soviets, remained a deeply contentious issue for decades.
Both regimes attempted to destroy Polish culture, identity, and political life.
Polish Resistance and Government-in-Exile
Though defeated militarily, Poland did not cease to exist as a state. The Polish government-in-exile was established first in France and later moved to London after the fall of France in 1940. Polish armed forces regrouped abroad and fought alongside the Allies throughout the war—in France, the UK, North Africa, and on the Eastern Front.
Inside occupied Poland, one of the largest and most effective underground resistance movements in Europe emerged: the Home Army (Armia Krajowa). It conducted sabotage, intelligence gathering, and guerilla warfare against both German and Soviet forces.
Consequences
- Outbreak of World War II: The invasion triggered Britain and France’s declarations of war, officially beginning WWII.
- Destruction of the Polish State: Poland ceased to exist as an independent entity and suffered brutal occupation for the next six years.
- Soviet Expansion: The USSR annexed eastern Poland, incorporating it into the Ukrainian and Belarusian SSRs—territorial changes largely ratified by the Allies after the war.
- Genocide and War Crimes: The occupation set the stage for the Holocaust, with Poland becoming the epicenter of Nazi extermination camps.
- Legacy of Betrayal: The perceived failure of the Western Allies to assist Poland meaningfully led to deep resentment. At war’s end, Poland was not restored to full independence but instead became a Soviet satellite under communist rule.
Conclusion
The Invasion of Poland was more than just the start of World War II—it was a tragic episode that led to the devastation of an entire nation and the suffering of millions. It showcased the dangers of totalitarian ideologies, the limitations of appeasement, and the brutal consequences of international power politics. While Poland was defeated militarily, its people continued to fight and resist, and the memory of 1939 became a powerful symbol of resilience and sacrifice in Polish history. The invasion also served as a grim prelude to the horrors that would unfold across Europe in the years that followed.
