Early history Before the arrival of the
Teutonic Order, the river valley was here settled by the
Nadruvians, as evidenced by traces of settlements and fortifications found in the area. Teutonic overlordship was established around 1388, but the town is mentioned for the first time in written sources in 1539 as
Darkyem. In 1454, the region was incorporated by King
Casimir IV Jagiellon to the
Kingdom of Poland upon the request of the anti-Teutonic
Prussian Confederation. After the subsequent
Thirteen Years' War, since 1466, it formed part of Poland as a
fief held by the Teutonic Order, and after 1525 it was located in
Ducal Prussia, a vassal duchy of Poland. It was settled by
Lithuanian,
Polish and
German colonists. Located in the transitional area between
Masuria in the south and
Lithuania Minor in the north, the town and surrounding villages had a mixed population with both many Poles Soon afterwards, the town plan was revised with a market square and a new
grid plan. An influx of immigrants followed (in 1725, 103 of the 742 registered inhabitants came from
Salzburg) and
craft production of leather and cloth established in the town. Polish Jews took part in local fairs, and their products were the most popular. In , a garrison of the
Bosniak Corps was established. In the 1740s, the local cloth industry declined, and many clothmakers moved to
Insterburg,
Tilsit or Poland. The sole prosperous cloth business in the town at that time sold its products to the Polish Royal Guard. During the Napoleonic Wars, the first Jews settled permanently, arriving from
Poznań. In 1818, it became a district seat. By 1852, the town gained road connections with Insterburg and
Gumbinnen, and in 1870 with Gołdap. Nine annual
fairs were organized in the town in the late 19th century. Due to its location on the
Angrapa River, a power station established in the watermill was already in 1880 able to produce electrical light for the town.
20th century During
World War I, the town was captured by Russians in 1914. It was heavily damaged during fighting but rebuilt after
garden city ideals following the war, with financial support from the city of
Dresden. In 1938, the Nazi government renamed the town to
Angerapp to erase traces of Lithuanian origin. Two labour camps of the
Reich Labour Service were operated in the town under
Nazi Germany. It was captured by the
3rd Belorussian Front of the
Red Army on 23 January 1945 in the course of the
East Prussian offensive. After Germany's defeat in
World War II, the town initially passed to Poland under its historic Polish name
Darkiejmy, however, it was soon unilaterally annexed by the
Soviet Union in violation of the Polish-Soviet border agreement. Its German populace was
expelled in accordance to the
Potsdam Agreement. It was renamed as Ozyorsk on 7 September 1946. In 1970, the Department of Printed Circuits was established as a branch of the Radiotechnical Measuring Instruments Factory in
Vilnius. ==Administrative and municipal status==