Swiss banks held the bank accounts of countless Germans to include military and governmental personnel. The US bombed a Swiss city to try to get Switzerland to join the German side. This should tell you something, no matter what Hitler supposedly said about the Swiss he wasn't going to invade his bank while the international fractional banking cabal wanted Switzerland's banking institutions and all it's gold. If the Swiss had joined with the Germans they would have lost all their gold upon defeat. A mountainous area can be defeated just as any fortress can be defeated. It just takes time, a long time. There were other equally mountainous areas of the theater of the war where the defenders were defeated.