Second Polish Republic
Second Polish Republic was name of Polish state from 1918 (end of WWI) through 1939 (start of WWII). When its borders were fixed in 1922 after several wars, it had borders with Czechoslovakia, Weimar Republic (Germany), Free City of Danzig, Latvia, Lithuania, Romania and Soviet Union. Józef Piłsudski was the leader during most of the state's existence.
The Second Polish Republic, in 1939, was invaded by the Greater German Reich and the U.S.S.R. after refusing to make territorial changes towards Germany. Poland was then fully occupied by both countries 39 days later. The government fled to the United Kingdom and became the Polish government-in-exile, while based in London. It continued it's existence in Poland as the Polish Underground State until 1945 when Poland was released but made a communist, soviet, satellite state. The pre-war government remained in exile until the collapse of Communism in 1990.