ccupation of Vilnius was greatly resented by Lithuania; there were no diplomatic relations between the two states for most of the period between the two world wars.
Acquired during the Klaipėda Revolt of 1923, the Klaipėda Region was ceded to Germany after a German ultimatum in March 1939. During the interwar period, the domestic affairs of Lithuania were controlled by the authoritarian President, Antanas Smetona and his party, the Lithuanian Nationalist Union, who came to power after the coup d'état of 1926.
The Soviet Union returned Vilnius to Lithuania after the Soviet invasion of Eastern Poland in September 1939. In June 1940, the Soviet Union occupied and annexed Lithuania in accordance to the secret protocols of Molotov–Ribbentrop Pact. A year later the Soviet Union was attacked by Nazi Germany, leading to the Nazi occupation of Lithuania. The Nazis and their collaborators murdered around 190,000 Jews of Lithuania (91% of the pre-war Jewish community) during the Holocaust.
After the retreat of the German armed forces, the Soviets re-established the annexation of Lithuania in 1944. Under border changes promulgated at the Potsdam Conference in 1945, the former German Memelland, with its Baltic port Memel (Lithuanian: Klaipėda), was again transferred to Lithuania, or as it was after 1945 the Lithuanian SSR. Most German residents of the area had fled in the final months of World War II.
The Soviets engaged in massive deportations of Lithuanians to Siberia, complete nationalisation and collectivisation and general sovietization of everyday life. From 1944 to 1952 approximately 100,000 Lithuanian partisans fought a guerrilla war against the Soviet system. An estimated 30,000 partisans and their supporters were killed, and many more were arrested and deported to Siberian gulags. It is estimated that Lithuania lost 780,000 people during World War II.
The advent of perestroika and glasnost in the late 1980s allowed the
