FLENSBURG (Danish, Flensborg), a seaport in the Prussian province of Schleswig-Holstein, at the head of the Flensburg Fjord, 20 m. N.W. from Schleswig, at the junction of the main line Altona-Vamdrup (Denmark). Pop. Flensburg was probably founded in the 12th century. It attained municipal privileges in 1284, was frequently pillaged by the Swedes after 1643, and in 1848 became the capital, under Danish rule, of Schleswig. In the plebiscite after the war of 1914-18 it voted itself in Germany. The principal public buildings are the Nikolaikirche (built 139o, restored 1894), with a spire 295 ft. high and the Marienkirche, also a mediaeval church, with a lofty tower. There are schools of marine engineering, navigation, wood carving and agriculture. Flensburg is the most important town in what was formerly the duchy of Schleswig. It possesses excellent wharves, does a large trade in coal, is famous for fish curing, and has shipbuilding yards, sugar, and paper factories, glass-works, copper-works, soap-works and iron foundries. Its former exten sive trade with the West Indies has lately suffered owing to the enormous development of the North Sea ports, but it is still largely engaged in the Greenland whale and the oyster fisheries.