Suwałki Region in the context of "Witherite"

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 occupies much of the Masurian Lake District. Administratively, it is part of the Warmian–Masurian Voivodeship (administrative area/province). Its biggest city, often regarded as its capital, is Ełk. The region covers a territory of some 10,000 km which approximately 500,000 people inhabit.

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.

The Polish–Lithuanian War was an undeclared war fought in the aftermath of World War I between newly independent Lithuania and Poland, with fighting mainly in the Vilnius and Suwałki regions, which was part of the Lithuanian Wars of Independence and lasted from May 1919 to 29 November 1920. From the spring of 1920 onward, the conflict happened alongside the wider Polish–Soviet War and was affected by its progress. It was subject to unsuccessful international mediation at the Conference of Ambassadors and the League of Nations.

After World War I, the military and political situation in the region was chaotic, as multiple countries, notably Lithuania, Poland, and Soviet Russia, vied with each other over control of overlapping areas. The Polish–Lithuanian conflict was centered on Vilnius, which the Council of Lithuania declared the capital of the restored Lithuanian state. Control of Vilnius was transferred from Germans to Poles on January 2, 1919, but the Polish paramilitary lost the city to the Bolsheviks on January 5. The Polish Army seized Vilnius again on April 19, 1919 and came in contact with the Lithuanian Army fighting in the Lithuanian–Soviet War. Despite the antagonism over Vilnius, the Lithuanian and Polish armies sometimes cooperated when fighting against a common enemy, the Bolsheviks. As Lithuanian–Polish relations worsened, the Entente drew two demarcation lines in hopes to stall further hostilities. The lines did not please either side and were ignored. The first clashes between Polish and Lithuanian soldiers occurred on April 26 and May 8, 1919, near Vievis. With the Polish coup against the Lithuanian government failing in August 1919, the front stabilized until the summer of 1920.