Following Nazi Germany's defeat in World War II in 1945, war-torn East Prussia was divided at Joseph Stalin's insistence between the Soviet Union (the Kaliningrad Oblast became part of the Russian SFSR, and the constituent counties of the Klaipėda Region in the Lithuanian SSR) and the People's Republic of Poland (the Warmian-Masurian Voivodeship).

An estimated 300,000 died either in wartime bombing raids, in the battles to defend the province, through mistreatment by the Red Army, or from hunger, cold and disease.

Adjacent to the Curonian Lagoon and the lower reaches of the Neman river could be found the Elchniederung [de], a vast partially-drained bog, much of it below sea-level.

At the instigation of Duke Konrad I of Masovia, the Teutonic Knights took possession of Prussia in the 13th century and created a monastic state to administer the conquered Old Prussians.

Walter von Cronberg, the next Grand Master, was enfeoffed with the title to Prussia after the Diet of Augsburg in 1530, but the Order never regained possession of the territory.

In return for supporting Emperor Leopold I in the War of the Spanish Succession, Elector Frederick III was allowed to crown himself "King in Prussia" in 1701.

Approximately one-third of East Prussia's population died in the Great Northern War plague outbreak and famine of 1709–1711,[11] including the last speakers of Old Prussian.

In 1724, Frederick William I prohibited Poles, Samogitians and Jews from settling in Lithuania Minor, and initiated German colonization to change the region's ethnic composition.

The French Grande Armée troops immediately took up pursuit but were delayed in the Battle of Eylau on 9 February 1807 by an East Prussian contingent under General Anton Wilhelm von L'Estocq.

Napoleon had to stay at the Finckenstein Palace, but in May, after a siege of 75 days, his troops led by Marshal François Joseph Lefebvre were able to capture the city of Danzig, which had been tenaciously defended by General Count Friedrich Adolf von Kalkreuth.

Frederick William and Queen Louise met with Napoleon for peace negotiations, and on 9 July the Prussian king signed the Treaty of Tilsit.

This stagnancy in population despite a high birth surplus in eastern Germany was because many people from the East Prussian countryside moved westward to seek work in the expanding industrial centres of the Ruhr Area and Berlin (see Ostflucht).

The Klaipėda Territory (Memelland), a League of Nations mandate since 1920, was occupied by the Lithuanian Armed Forces in 1923 and annexed without giving the inhabitants a choice by ballot.

[20] This period was characterized by efforts to collectivize the local agriculture and ruthlessness in dealing with his [clarification needed] critics inside and outside the Nazi Party.

[25] Koch's industrialization plans provoked conflict with Richard Walther Darré, who held the office of the Reich Peasant Leader (Reichsbauernführer) and Minister of Agriculture.

[26] In 1938 the Nazis changed about one-third of the toponyms of the area, eliminating, Germanizing, or simplifying a number of Old Prussian, as well as those Polish or Lithuanian names originating from colonists and refugees to Prussia during and after the Protestant Reformation.

In 1939 East Prussia had 2.49 million inhabitants, 85% of them ethnic Germans, the others Poles in the south who, according to Polish estimates numbered in the interwar period around 300,000–350,000,[28] the Latvian speaking Kursenieki, and Lietuvininkai who spoke Lithuanian in the northeast.

Most German East Prussians, Masurians, Kursieniki, and Lietuvininkai were Lutheran, while the population of Warmia was mainly Roman Catholic due to the history of its bishopric.

The Polish resistance was active in the province, both in the annexed pre-war territory of Poland, and in the pre-war territory of East Prussia, with activities in the latter including distribution of Polish underground press,[41] sabotage actions, executions of Nazis, theft of German weapons, ammunition and equipment,[42] and organization of transports of POWs who escaped German POW camps via the ports of Gdańsk and Gdynia to neutral Sweden.

Winston Churchill (The Second World War, Book XII) had erroneously believed it to be "a modernized heavily defended fortress" and ordered its destruction.

Gauleiter Erich Koch delayed the evacuation of the German civilian population until the Eastern Front approached the East Prussian border in 1944.

Thousands lost their lives during the sinkings (by Soviet submarine) of the evacuation ships Wilhelm Gustloff, the Goya, and the General von Steuben.

An estimated 300,000 died either in wartime bombing raids, in the battles to defend the province, or through mistreatment by the Red Army or from hunger, cold and disease.

[5] However, most of the German inhabitants, which then consisted primarily of women, children and old men, did manage to escape the Red Army as part of the largest exodus of people in human history: "A population which had stood at 2.2 million in 1940 was reduced to 193,000 at the end of May 1945.

Most of the German population of the province had left during the evacuation at the end of the war, but several hundreds of thousands died during the years 1944–46 and the remainder were subsequently expelled in accordance with the Potsdam Agreement.

The rest were mostly people from neighbouring areas located right next to East Prussia (almost 44% came from Masovia, Sudovia, Podlachia and pre-war Polish Pomerania) and southern Poland (≈16%).

[57] However, the majority of East Prussian Polish and Lithuanian inhabitants were Lutherans, not Roman Catholics like their ethnic kinsmen across the border in the Russian Empire.

Only in southern Warmia Catholic Poles – so called Warmiaks (not to be confused with predominantly Protestant Masurians) – comprised the majority of population, numbering 26,067 people (≈81%) in county Allenstein (Polish: Olsztyn) in 1837.

[57] Another minority in pre-war East Prussia were ethnically Russian Old Believers, also known as Philipponnen – their main town was Eckertsdorf (Wojnowo), in Sensburg district.

Since 1875, with the strengthening of self-rule, the urban and rural districts (Kreise) within each province (sometimes within each governorate) formed a corporation with common tasks and assets (schools, traffic installations, hospitals, cultural institutions, jails etc.)