High Quality Content by WIKIPEDIA articles! The Sejny Uprising or Seinai Revolt (Polish: Powstanie sejnenskie, Lithuanian: Seinu sukilimas) refers to a Polish uprising in the ethnically-mixed area surrounding Sejny (Lithuanian: Seinai) against the Lithuanian authorities in August 1919. When German forces, which occupied the territory during World War I, retreated from the area, the administration was handed to the Lithuanians. Trying to prevent an armed conflict between Poland and Lithuania, the Entente drew a demarcation line, known as the Foch Line. The line assigned much of the disputed Suwalki (Suvalkai) Region to Poland and required the Lithuanian Army to retreat. While the Lithuanians retreated from some areas, they refused to leave Sejny. Polish irregular forces began the uprising on August 23, 1919, and soon received support from the regular Polish Army. After several military skirmishes, Polish forces secured Sejny and Lithuanians retreated behind the Foch Line. Данное...