The signing of a nonaggression pact with Germany in 1934 should have guaranteed that Poland would avoid conflict with the newly emerging German government led by Adolf Hitler. The rearmament of Germany’s military for the first time since World War I was ignored by most countries, including Britain and France. By 1938, Hitler had succeeded in annexing Austria and parts of Czechoslovakia. By the summer of 1939, Germany was in full control of Czechoslovakia and on the brink of penning a treaty with Russia that would divide Poland between them. German tanks rolled into Poland on September 1, 1939. The invasion of Poland had begun.
The German invasion of Poland is seen as the point at which the world began its journey toward a second world war. The years of German occupation of Poland lasted only from 1939 through 1945, but during that six-year period, more than six million Polish citizens died and most of its cities and towns were destroyed.
Although its army fell to Germany’s superior might within weeks of the 1939 invasion, the Polish government continued to operate in exile under the leadership of Wladyslaw Sikorski. General Sikorski established a government-in-exile in England. Some members of the Polish military fought side by side with British forces in North Africa and in Italy while other Polish fighters joined forces with units of the Soviet Union. Eventually, Josef Stalin withdrew Russian support for the Polish government-in-exile, but Polish troops recruited from people of Polish descent living in Russia continued to play a significant role in the Soviet army that fought against the German invaders.
Polish resistance against German aggression took place away from the battlefield as well as on it. Polish agents delivered secret information to British intelligence about Enigma, the code machine that Germany thought was top secret. The information about Enigma allowed the British to intercept and decipher coded messages between German government and military leaders.
Resistance to Germany continued in Poland even after the defeat of the Polish army. An underground resistance movement carried out guerrilla-type operations against German units. The resistance movement in Poland claimed to have nearly 400,000 members and supporters to carry out clandestine operations against the German military.
By 1944, Allied forces were securing victories over Germany throughout Europe. A push by military units of the Soviet Union toward Warsaw signaled an opportunity for the Polish resistance to strike at German forces in Warsaw. When the Russian army abruptly put the brakes to its drive toward Warsaw, German forces were free to focus their attention on the Polish resistance units instead. Before they left Warsaw, German troops destroyed almost the entire city in retaliation for the unsuccessful attack by the Polish resistance.
German occupation of Poland ended in 1945 when Russian forces drove them from the country. Poland would remain under the control of the Soviet Union until the Solidarity movement in the 1980s.