Polish–Czechoslovak border conflicts - Wikipedia
https://en.wikipedia.org/wiki/Polish–Czechoslovak_border_conflictsAfter the end of World War I, both of the two newly created independent states of the Second Polish Republic and First Czechoslovak Republic claimed the area of Cieszyn Silesia. Czechoslovakia claimed the area partly on strategic and ethnic grounds, but especially on economic and historic grounds. The disputed area was part of the historic Czech lands of Bohemian Crown. The only railway from Czech territory to eastern Slovakia ran through this area (Košice …