The Dukla operation, which had originally been planned to coincide with the Uprising, began on September 9 in Poland and by early October the Soviet Red Army and Czechoslovak brigades had reached the Slovak border.
Days later, on October 6, the Soviet and Czechoslovak brigades launched an attack over the border into Czechoslovakia. The largest tank battle on Czechoslovak soil took place here on 25th – 28th October 1944, in a place now also known as the Death Valley.
The battle, now commemorated with a large memorial at the Dukla Pass, was a slow and deadly grind. More than 100,000 soldiers died, and many are still buried in the area. The Dukla memorial alone holds some 8,000 graves. A cemetery in nearby Hunkovce holds the bodies of around 2,000 German soldiers.