Sejny Uprising

Lt. Adam Rudnicki, leader of the Sejny Uprising, and his colleagues. August 1919.

Date	August 22 – September 7, 1919
Location	Suwałki Region
Result	Lithuanians retreated behind the Foch Line; Poland secured Sejny

Belligerents

Polish Military Organization (PMO)

41st Infantry Regiment

Lithuanian Sejny Command

1st Reserve Battalion

Commanders and leaders

Adam Rudnicki
Mieczysław Mackiewicz

Kazys Ladiga

Strength

900–1,200 PMO volunteers
800 regular troops

900 regular troops
300 volunteers

Casualties and losses

37 killed in action
70 wounded

The Sejny Uprising or Seinai Revolt (Polish: Powstanie sejneńskie, Lithuanian: Seinų sukilimas) refers to a Polish uprising against the Lithuanian authorities in August 1919 in the ethnically mixed area surrounding the town of Sejny (Lithuanian: Seinai). When German forces, which occupied the territory during World War I, retreated from the area in May 1919, they turned over administration 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 Suwałki (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.

The uprising did not solve the larger border conflict between Poland and Lithuania over the ethnically mixed Suwałki Region. Both sides complained about each other's repressive measures. The conflict intensified in 1920, causing military skirmishes of the Polish–Lithuanian War. Sejny changed hands frequently until the Suwałki Agreement of October 1920, which left Sejny on the Polish side. The uprising undermined the plans of Polish leader Józef Piłsudski, who was planning a coup d'état in Lithuania to replace the Lithuanian government with a pro-Polish cabinet, that would agree to a union with Poland (the proposed Międzymorze federation). Because the Sejny Uprising had prompted the Lithuanian intelligence to intensify its investigations of Polish activities in Lithuania, they discovered plans for the coup and prevented it, arresting Polish sympathizers. These hostilities in Sejny further strained the Polish–Lithuanian relations.

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Wikipedia