Masuria (Polish: Mazury [maˈzurɨ] ⓘ; Masurian: Mazurÿ; German: Masuren [maˈzuːʁən] ⓘ) is an ethnographic and geographic region in northern and northeastern Poland, known for its 2,000 lakes.

Masuria is bordered by Warmia, Powiśle and Chełmno Land in the west, Mazovia in the south, Podlachia and Suwałki Region in the east, and Lithuania Minor in the north.

Some of the earliest archeological finds in Masuria were found at Dudka and Szczepanki sites and belonged to the subneolithic Zedmar culture.

[6][7] In AD 98 Tacitus described one of the tribes living near the Baltic Sea (Latin: Mare Suebicum) as Aestiorum gentes and amber-gatherers.

The number of Polish settlers grew significantly again at the beginning of the 15th century, especially after the first and the second treaties of Thorn (Toruń), in 1411 and 1466 respectively, following the Thirteen Years' War and the final defeat of the order.

The Knights untied their bonds to the Catholic Church and became land-owning noblemen and the Duchy of Prussia was established as a vassal state of Poland.

The westernmost part of Masuria, the Osterode (Ostróda) county, in 1633 came under the administration of one of the last dukes of the Piast dynasty, John Christian of Brieg.

In 1656, during the Battle of Prostki, the forces of Polish–Lithuanian Commonwealth, including 2,000 Tatar raiders, beat the allied Swedish and Brandenburg army capturing Bogusław Radziwiłł.

The last group of refugees to emigrate to Masuria were the Russian Philipons (as 'Old Believers' opposed to the State Church) in 1830, when King Frederick William III of Prussia granted them asylum.

[23] After the death of Albert Frederick, Duke of Prussia in 1618, his son-in-law John Sigismund, Margrave of Brandenburg, inherited the duchy (including Masuria), combining the two territories under a single dynasty and forming Brandenburg-Prussia.

In this climate a first resistance defending the rights of rural population was organized, according to Jerzy Mazurek usually by some teachers engaged in publishing Polish language newspapers.

In contrast to the Prussian-oriented periodicals, in the late 19th century such newspapers as Przyjaciel Ludu Łecki and Mazur were founded by members of the Warsaw-based Komitet Centralny dla Śląska, Kaszub i Mazur (Central Committee for Silesia, Kashubia and Masuria), influenced by Polish politicians like Antoni Osuchowski or Juliusz Bursche, to strengthen the Polish identity in Masuria.

[44][45][46][47] After World War I the editor of the Polish language Mazur described the Masurians as "not nationally conscious, on the contrary, the most loyal subjects of the Prussian king".

Masurian newspapers like the Przyjaciel Ewangeliczny and the Gazeta Polska dla Ludu staropruskiego w Westfalii i na Mazurach but also the German language Altpreußische Zeitung were published.

[69] According to the Rybno administration, most active Poles in that subregion included Jóżwiakowscy, Wojnowscy, Grzeszczowscy families working under the guidance of politician Leon Wojnowski who protested German attempts to remain Działdowo a part of Germany after the war; other local pro-Polish activists were Alfred Wellenger, Paczyński, Tadeusz Bogdański, Jóźwiakowski.

However, Masuria was still largely agrarian-oriented and suffered from the economic decline after World War I, additionally badly affected by the creation of the so-called Polish Corridor, which raised freight costs to the traditional markets in Germany.

[98] Before the war the Nazi German state sent undercover operatives to spy on Polish organisations and created lists of people that were to be executed or sent to concentration camps.

[99] With the start of the German invasion of Poland and World War II on 1 September 1939, the German minority in the parts of Masuria attached to Poland after World War I organised themselves in paramilitary formations called Selbstschutz (selfdefense) and begun to engage in massacres of local Polish population; Poles were imprisoned, tortured and murdered[103][104] while Masurians were sometimes forcefully placed on Volksliste.

In addition, the Einsatzgruppe V Nazi paramilitary death squads entered German-occupied Działdowo to commit crimes against the Polish population.

[107] Only some of the Polish activists from Działdowo County were caught by the Germans, as most managed to flee and hide under assumed names in the General Government (German-occupied central Poland).

Notable victims included the Polish bishops Antoni Julian Nowowiejski and Leon Wetmański, as well as the nun Mieczysława Kowalska.

[115] In Masuria, Germany also established and operated the Stalag I-B and Oflag 63 prisoner-of-war camps for Polish, Belgian, French, Italian, Serbian and Soviet POWs,[116] and built the Wolf's Lair, Adolf Hitler's first Eastern Front military headquarters where the 20 July assassination attempt occurred in 1944.

[117] In 1943, "Związek Mazurski" was reactivated secretly by Masurian activists of the Polish Underground State in Warsaw and led by Karol Małłek.

[120] In the final stages of World War II, Masuria was partially devastated by the retreating German and advancing Soviet armies during the Vistula-Oder Offensive.

[122][123][124] Most of the population fled to Germany or was killed during or after the war, while those which stayed were subject to a "nationality verification", organised by the communist government of Poland.

Many unverified Masurians were imprisoned and accused of pro-Nazi or pro-American propaganda, even former pro-Polish activists and inmates of Nazi concentration camps were jailed and tortured.

[130] In 1950, 1,600 Masurians left the country and in 1951, 35,000 people from Masuria and Warmia managed to obtain a declaration of their German nationality by the embassies of the United States and Great Britain in Warsaw.

[131] In December 1956, Masurian pro-Polish activists signed a memorandum to the Communist Party leadership: "The history of the people of Warmia and Masuria is full of tragedy and suffering.

The majority (over 100 thousand) gradually left, and after the improvement of German-Polish relations by the German Ostpolitik of the 1970s, 55,227 persons from Warmia and Masuria moved to West Germany in between 1971 and 1988.

[133] Today, between 5,000 and 6,000 Masurians still live in the area, about 50 percent of them members of the German minority in Poland; the remaining half is ethnic Polish.