When Czechoslovakia was building its military fortification in the 1930s, the generals decided to use the Bruntál region highlands. They build a series of small bunkers, called řopíky, which you can still see in many locations. Thus, the fortification was made stronger, due the difficult highland landscape.
The line was basically finished, except for a small area between Bruntál and Opava. Military experts of the German army were aware of this and planned to drop parachutists here to break through the line. They called it the Bruntál Operation. In the end, the operation did not take place, since Czechoslovakia ceded the fortification to Germany after the Munich Agreement.
Wehrmacht executed this operation as a military exercise in the fall of 1938. The training jump and follow-up seizure of bunkers showed that attacking the units would have failed in reality. Adolf Hitler visited the existing bunker by Nové Hřminovy. You can read about this visit on the signboard of the local educational trail.