East Prussia in eastern Europe was the original heartland of Prussia. It is an area rish farmland, lakes and forest bordered to the east and south by the Russian Empire and to the west by the Baltic Sea. The main city was Konigsberg, home of philosopher Immanuel Kant. The region featured very large estates controlled by Junker elites and nobles.
The province was a battleground in 1914-15, when, following the outbreak of the First World War Russian armies invaded the province but were decisively defeated at the Battle of Tannenberg in 1914 and the Battle of the Masurian Lakes. Following Germany's defeat in 1918, East Prussia remained part of Germany (with the exception of the port of Memel, seized by newly-independent Lithuania), but was separated from the rest of the country by a strip of Polish territory known as the Polish Corridor. In 1939 Nazi Germany forced Lithuania to relinquish Memel.
After the Second World War, The Germans all fled and East Prussia was divided between the Soviet Union and Poland. Memel - renamed Klaipeda - became part of the Soviet Republic of Lithuania; northern East Prussia, with Konigsberg (renamed Kaliningrad), became part of the Russian republic (known as Kaliningrad Oblast), and the southern part was ceded to Poland.