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.

By the end of World War One there were certain polish centers of power, the most prominent was Regency Council, established by the act of Act of 5 November, which used to be temporary head of state during the interregnum in Kingdom of Poland. On the emigration, in France there was Polish National Comitee, led by Roman Dmowski. On the former Austro-Hungarian part (Kingdom of Galicia and Lodomeria and Cieszyn Silesia) there was Polish Liquidation Committee, led by Wincenty Witos. A provinsional government called Provisional People's Government of the Republic of Poland, was formed in Lublin uder the Ignacy Daszyński.
On the 10 November 1918 Józef Piłsudski was released from the prison in Magdeburg in Germany, returned to Poland and day later (11.11) achieved a military power from the regency Council. On 14 November 1918 he achieved a full rule and became Chief of the State, a temporary head of country until election of the president while regency council got dissolved, he proclaimed Polish independence to other nations on 16 November 1918 by a telegram. Piłsudski issued a decree of basic functioning of Polish Republic on 22 November 1918 which declared that Poland is not monarchy anymore.
The Second Polish Republic, in 1939, refused to make territorial changes towards Germany. The Invasion of Poland (1939) brought the occupation of Poland by the German Reich and the Soviet Union 39 days later.
The government fled to the United Kingdom (UK) and became the Polish government-in-exile, while based in London. It continued its existence in Poland as the Polish Underground State until 1945 when Poland was released but made a Communist satellite state of the Soviet Union. The pre-war government remained in exile until the collapse of Communism in 1990. Afterwards, it dissolved and handed its roles over to the current Polish State.
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