Eastern_Silesia
Eastern Silesia was formerly the Austrian crownland Austrian Silesia, which was occupied by Czechoslovakia after World War I. It had an area of 1,987 sq mi (5,146 km2), with a population of 680,422 in 1900. The capital was Opava. Plans for a plebiscite fell through, and the area was divided between Czechoslovakia and Poland.
The territory was entered by the Czech military on 23 January 1919, after negotiations with Poland broke down.
A final agreement on the border was reached on 28 July 1920.