Prussia (Prussian: Prūsa; Polish: Prusy [ˈprusɨ] ⓘ; Lithuanian: Prūsija; Russian: Пруссия [ˈprusʲ(ː)ɪjə] ⓘ; German: Preußen [ˈpʁɔʏsn̩] ⓘ; Latin: Pruthenia/Prussia/Borussia) is a historical region in Central Europe on the south-eastern coast of the Baltic Sea, that ranges from the Vistula delta in the west to the end of the Curonian Spit in the east and extends inland as far as Masuria, divided between Poland, Russia (Kaliningrad Oblast) and Lithuania.

[2][3] The region's inhabitants of the Middle Ages were first called Bruzi in the brief text of the Bavarian Geographer and have since been referred to as Old Prussians, who, beginning in 997 AD, repeatedly defended themselves against conquest attempts by the newly created Duchy of the Polans.

After the area was reintegrated with Poland in 1466 both names were in use: Pomerania was used when referring to the Pomeranian Voivodeship (Gdańsk Pomerania) and the Chełmno Voivodeship, while Royal Prussia was used as the name of the wider province, which, however, also included the Malbork Voivodeship and the Prince-Bishopric of Warmia, covering the Prussian historical areas of Pomesania, Pogesania and Warmia, the only actual Prussian territories of the province, while the rump Teutonic state, called the Monastic Prussia thereafter, formed a part of Poland as a fief,[5] finally secularised in 1525 to become the Lutheran Ducal Prussia.

In contrast, the Lauenburg and Bütow Land was annexed in 1777 immediately into the Province of Pomerania, but remained outside the Holy Roman Empire and was incorporated in 1815 only into its successor, the German Confederation, continuing to be a part of the Diocese of Chełmno.

[7] Since its conquest by the Soviet Army with evacuation and expulsion of the German-speaking inhabitants in 1945 in accordance with the Potsdam Agreement, the region of Prussia remains divided between northern Poland (most of the Warmian-Masurian Voivodeship, and the four counties of Pomeranian Voivodeship east of Vistula), Russia's Kaliningrad exclave, and southwestern Lithuania (former Klaipėda Region).

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

[14] At the end of the Viking Age, the sons of Danish kings Harald Bluetooth and Cnut the Great launched several expeditions against the Prussians.

Old Prussian, or related Western Baltic dialects, may have been spoken as far southeast as Masovia and even Belarus in the early medieval period, but these populations would probably have undergone Slavicization before the 10th century.

The Duke finally invited the Teutonic Knights in 1226, expelled by force of arms by King Andrew II of Hungary in the previous year following their attempts to build their own state within Transylvania.

The Polish region of Pomerelia (including Gdańsk Pomerania and the city of Gdańsk as its parts) which was never inhabited by the Old Prussians, and which was called Pomorze ('Pomerania') in Polish language since the Early Middle Ages, was forcibly occupied by the monastic state of the Teutonic Knights in 1308, following an invasion of Poland under the pretext of aiding the King Władysław I Łokietek to quell a rebellion against him, incited by a conspiracy of the Margraviate of Brandenburg with the local Swienca family.

The possession of Danzig and Pomerelia by the Teutonic Order was questioned consistently by the Polish kings Władysław I and Casimir the Great in legal suits in the papal court in 1320 and 1333.

Subsequent rebellions organized by the local population against the Teutonic state, initially by the Lizard Union and later by the Prussian Confederation, both pledging allegiance to the Polish king, caused the Thirteen Years' War which ultimately led to the Second Peace of Thorn, when most of the region and was reclaimed by Poland and henceforth formed the bulk of Royal Prussia.

The latter also included, however, also the truly Prussian historical areas of Prince-Bishopric of Warmia, as well as the Malbork Land comprising northern parts of Pomesania and Pogesania.

Initially enjoying broad autonomy including an own local legislature, the Prussian Estates, and maintaining its own laws, customs and rights, Royal Prussia was ultimately re-absorbed directly into the Crown of the Kingdom of Poland, following the Union of Lublin in 1569.

The locally spoken language differed among social classes, with the aristocracy and urban burghers initially highly Germanised as a result of earlier Teutonic policies, but gradually shifting towards Polish in the later years, while the peasantry continued as predominantly Kashubian- and Polish-speaking West of Vistula; the part East of Vistula was predominantly German-speaking, with decreasing number of Old Prussian and increasing number of Polish minorities.

Its bulk which included the historically Prussian Malbork Land (northern parts of Pomesania and Pogesania) but also the historically Polish Pomerelia (Vistula Pomerania) formed the newly established province of West Prussia, while the name Pomerania/Pomerelia was avoided by Prussian and later German authorities in relation to this region, aiming to eradicate its usage completely.

During the Napoleonic era the Greater Polish territories and the Chełmno Land formed part of the Duchy of Warsaw following the Treaties of Tilsit, and Danzig was granted a status of a Free City.

The annexation was associated with another attempt to artificially expand the meaning of the designation of Prussia by transferring the northern part of Netze District, a fragment of Greater Poland detached from its bulk (the Grand Duchy of Posen), to West Prussia, while the district's easternmost fragment was awarded to the Russian-ruled Congress Poland.

[7] The area was occupied and illegally annexed by the Nazi Germany during the invasion of Poland in 1939, as well as renamed Reichsgau Danzig-Westpreussen, with numerous German atrocities against the local population.

In the aftermath of the German attack on the Soviet Union in June 1941, a further German attempt to expand the meaning of the designation of Prussia was undertaken, when the westernmost portion of Soviet Belarus (which, until 1939, belonged to the Polish state), was placed under the German Civilian Administration (Zivilverwaltungsgebiet) as the Bialystok District, an entity in association with (but not part of) East Prussia, nevertheless it was also denoted on some Nazi maps as South East Prussia, with both territories remaining under common management and leadership of Erich Koch, a war criminal sentenced after the war by a Polish court to death, albeit with his penalty later commuted to life imprisonment.

Following the example of earlier German policies, there was a short-lived initiative in the Polish post-World War II government to rename the newly acquired original Prussia to an invented name of Masovian Pomerania; it was, however, quickly abandoned.

[31] In 1525, the last Grand Master reigning in the State of the Teutonic Order, Albert of Brandenburg, a member of a cadet branch of the House of Hohenzollern, adopted the Lutheran faith, resigned his position, and assumed the title of "Duke of Prussia".

The ducal capital of Königsberg, now Kaliningrad, became a centre of learning and printing through the establishment of the Albertina University in 1544 for not only the dominant German culture, but also the thriving Polish and Lithuanian communities as well.

[32] Rulership of Ducal Prussia passed to the senior Hohenzollern branch, the ruling Electors of Brandenburg, in 1618, and Polish sovereignty over the duchy ended in 1657 with the Treaty of Wehlau.

[34] Lithuanian culture thrived in the part of the region known as Lithuania Minor, while the Kursenieki lived along the coast in the vicinity of the Curonian and Vistula Spits.

The Klaipėda Region was returned to the Lithuanian SRR, while the remaining territory, annexed by the Russian FSSR, was in turn named the Kaliningrad Oblast in 1946.

In line with this assessment and the ideological justification of Recoverred Territories, the use of Prussia as a geographic designation was discouraged by the postwar authorities of Poland and the Soviet Union.

The policy was embraced by the Polish population who had hardly any sympathy for the legacy of Prussia, partially due to numerous attempts throughout history to annex various Polish territories with their subsequent artificial renaming as another part of Prussia in order to imply their originally Prussian history (see above), while the State of Prussia was perceived as a primary driving force for the Partitions of Poland with subsequent persecution and attempted Germanization of Poles, politically dominated by the Prussian Junkers with strong anti-Polish sentiment,[51] and finally, the German Province of East Prussia was regarded as an area of persecutions against Polish-speaking minority (Warmians, Masurians, Powiślans), but most importantly as a Nazi political stronghold whose existence as an exclave resulted in German irredentist demands towards Poland, blamed as one of the primary causes of the calamity of World War II and the ensuing German atrocities.

An important factor was also West Germany's rejection of the validity of the postwar Polish Western border on the Oder–Neisse line (until 1972 total, 1972-1991 de iure) rendering any attempts of Poles to remind or maintain the Prussian regional identity an easy target for the Polish authorities, interpreted as undermining future security and territorial integrity of Poland.

Since 1991, the name Prussia has, however, been re-acknowledged among Polish historians as the proper designation for the historic region, understood as defined by its original borders (excluding Pomerelia with Gdańsk Pomerania, the Chełmno and the Michałów Lands, as well as sometimes the Lubawa Land), resulting in its increasing usage in this context in the Polish scientific historical publications.