sentences:  In 1970, the Flensburg district was expanded to include the municipalities in the Amt of Medelby, formerly in the Südtondern district, and in 1974 it was united with the Schleswig district to form the district of Schleswig-Flensburg, whose district seat was the town of Schleswig.Flensburg thereby lost its function as a district seat, but it remained an independent (district-free) town.Until the middle of the 19th century Flensburg's municipal area comprised a total area of 2 639 ha.