The world in August 1939 was a world that held its breath. Fighting had ended in Spain, and the war in China had stagnated. But few people believed war would be avoided.
What was not certain was where and when. Adolf Hitler enjoyed tremendous popularity at home, and pro-Nazi factions were active in the United States, France, and Great Britain. His recent occupation of Czechoslovakia had raised alarms in capitals across Europe, even though many people ignorant of the violence and terror of the German political machine still looked to Hitler as a role model for their own governments.
Then the unthinkable happened. Joaquim von Ribbentrop, Hitler's Foreign Minister, went to Moscow the last week of August to secure a Nazi-Soviet Nonaggression Pact. Stalin, perhaps trying to buy time with Hitler himself, ordered his Foreign Minister, Molotov, to sign on August 21, 1939. When this agreement was announced to the world, it left out some key terms: the dismemberment of Poland.
Anyone reading Mein Kampf could see what Hitler thought of Poland. A former province of Czarist Russia, Poland had been guaranteed access to the sea — the “Free Corridor” of Danzig — by the League of Nations. This agreement separated Prussia from Greater Germany by cutting a path through to the seaport of Danzig. This angered Hitler and many Germans, who saw the land as the birthright of Germans everywhere.
Moreover, Poland was not an Aryan land. Poles were untermensch, “inferior people,” only good as slaves or corpses. After the dismemberment of Czechoslovakia, Hitler ordered his general staff to draw up plans for the invasion of Poland. The Germans would invade from the West, the Soviets from the East, and divide the country along previously agreed upon lines.
The SS took twelve prisoners out of Buchenwald, drove them to the Polish border and forced them to take poison after putting on Polish uniforms. The corpses were shot. An SS Officer yelled in Polish into a radio that they had come to invade Germany, and then the SS fled.
On September 1, 1939, Hitler told the Nazi Reichstag that Poland had tried to invade Germany, and the Wehrmacht was returning fire since 5:45 AM. Actually, in a carefully planned and highly mobile attack codenamed Fall Weiss (Case White) planned by Generalfeldmarschall Walther von Brauchitsch, German land, sea, and air forces were moving rapidly into Poland.
Poland's army in 1939 was totally unprepared for the new warfare it found itself in. Poland, like many armies in 1939, had large cavalry forces. What modern aircraft the Polish Air Force had were caught on the ground.
England and France wearily knew that they could not sacrifice Poland the way they had Czechoslovakia. On September 3, 1939, the Allies declared war against National Socialist Germany. The declaration did not save Poland. Lodz was about to fall, and Krakow fell on September 6. The fort at Danzig fell on September 7, after a week of direct fire from German battleships.
After a surprise Polish maneuver inflicted heavy casualties, the Germans rallied and took 100,000 prisoners. By September 16, German artillery ringed Warsaw, and the Nazis gave the Poles an ultimatum: surrender or face bombardment. The Poles demurred, and endured heavy shelling until September 27. German troops occupied Warsaw on October 1.
On September 17, Soviet troops entered Western Poland. They stopped at Brest-Litovsk, where Germans had allowed the Bolsheviks to withdraw Russia from World War I. Again the two nations carved up Poland.
Organized Polish resistance ended on October 6, 1939. Some 100,000 Polish soldiers would escape to form the Free Polish Brigade in England, where they would fight in the air during the Battle of Britain and on land after the Normandy invasion.
As the Red Army approached Warsaw during their 1944 offensive, Stalin ordered a halt. The pro-west Polish Home Army was destroyed by the Germans. Only after the western Poles were annihilated did the Red Army resume the advance.