Gau East Prussia was formed in 1933 in Nazi Germany initially as a district within the Free State of Prussia. In 1935, Germany's constituent states were dissolved and the Gaus replaced the states and their responsibilities. In 1939, East Prussia expanded following the annexation of the Klaipėda Region from Lithuania and the occupation of Poland, while a sliver of territory from the gau was transferred to Reichsgau Danzig-West Prussia. After Germany's attack on the USSR, the Belarusian city of Hrodna (German: Garten) also became part of the Gau.