Poland-Lithuania during the Second World War

The history of Poland-Lithuania during the Second World War relates to the history of Poland-Lithuania during World War II from the German invasion on September 1st, 1939 at the war's beginning until the end of the war in Europe on May 9th, 1945 following the capture of Berlin by the Soviet Union. Following the signing of the Molotov-Ribbentrop Pact, the nation was targeted for invasion by Nazi Germany and later the Soviet Union and its territories were to be divided and partitioned among the two nations which was finalized on October 6th, 1939 following the capitulation of Poland-Lithuania when the last unit surrendered and the nation was occupied. Despite the nation's defeat, its government and armed forces fled into exile and joined the British Army and French Army to form the Polish Armed Forces in the West that was formed in late 1939. An underground Polish state was eventually formed, but Lithuanian Separatists took up arms to and formed their own state with many collaborating with the Soviet Union and Nazi Germany in order to achieve a sovereign Lithuanian state. In late 1941, the Polish Armed Forces in the East was formed from Polish soldiers captured by the Red Army during their invasion of Poland along with the Lithuanian Red Army Divisions.

Despite its defeat, Poland-Lithuania provided major contributions towards the Allied war effort including devices that helped lead to cracking the German enigma code as early as 1939 and many exiled Polish soldiers made up the Polish Fighter Squadrons who fought in the Battle of Britain and scored the highest amount of shot down aircraft compared to other volunteer units. The 1st Polish Armored Division was formed and fought in the North African Campaign when it was first deployed in 1941, the same year Polish units were formed in the Soviet Union and began fighting on the Eastern Front against the Axis Powers. The Polish-Lithuanian Underground State was formed and lead a guerrilla war in occupied Poland during the war, though operations in Lithuania were difficult due to mixed support from the Lithuanian populace. Many ethnic Lithuanians formed resistance movements to fight against the occupation, while many fled and joined the Finnish Army and fought in the Winter War and later the Continuation War while others joined the Red Army Lithuanian Divisions and others formed their own underground state.

Throughout the entire war, Poland-Lithuania was subjected to the deadliest phase of the Holocaust, especially in Poland proper, where the Nazis set up concentration camps and deployed execution squads of the SS to liquidate the nation's Jewish population. Prior to the war, Poland-Lithunaia had a population of almost 4,000,000 Jews with most of them being located in Poland while the rest were in Lithuania. The high concentration of Jews lead to the majority of death camps being build in occupied territories and eventually lead to the deaths of three million Jews in total, 90% of the Jewish population, along with another 1,000,000 ethnic Poles while ethnic Lithuanians were largely spared with suspected communists and Soviet collaborators being sent to the camps. By the time the war had ended, Poland-Lithuania was annexed into the Soviet Union and turned into a Soviet republic while its government-in-exile remained. A total of seven million Polish-Lithuanians, both soldiers and civilians, were killed during the war making it the bloodiest war in Polish-Lithuanian history.

Background to war

German rearmament and tensions

In January 1933 the Nazi Party under the leadership of Adolf Hitler was elected into power with Hitler becoming the Chancellor of Germany and established a fascist dictatorship under the Nazi Party. Before long, a major program of rearmament was carried out leading to the reorganization of the German Army into the Wehrmacht including the reintroduction of conscription, formation of the first Luftwaffe squadrons, and the production of new tanks, known as Panzers. The rise of the Nazis concerned the Polish-Lithuanian government under Józef Piłsudski who feared a potential war with Germany and began to implementing new military reforms including conscription starting in 1934 where all male citizens aged 18-32 had to go through military training and register themselves eligible for conscription. This lead to draft riots in Vilnius where Lithuanian citizens, angered by years of suppression of Lithuanian separatism and culture by the Polish regime, rioted and refused to accept the draft. When Piludski died in 1935, his followers continued the military reforms, but were forced to meet demands from the Lithuanians as they feared a potential uprising that could be exploited by either Nazi Germany or the Soviet Union, the latter was viewed as the biggest threat to Poland-Lithuania due to experiences from the Polish-Lithuanian–Soviet War and the known anti-Polish sentiments and suppression operations carried out under Joseph Stalin and the NKVD during the Great Purge. The demands saw Lithuanians only serve a year of military service compared to two years for Polish citizens and the right for Lithuania to form its own domestic defensive army to use during wartime.