re: Why didn't Germany invade Switzerland?

Swiss were fresh and unblooded, they'd also spent the last decade modernizing their infantry and every time Hitler said or did something, the money towards it go that much more.

Germany could've won an invasion but the cost was prohibitive against the gain when they'd just sign up with the Axis when they had to.

Balkans also weren't entrenching like the Swiss did. So it was going to be. A very different guerilla war to manage.