Switzerland

[SwissBarbar]

Yes, but there are plenty of other countries that are neutral which are in the game e.g. Ireland/Sweden. Also, the Swiss didn't officially become neutral until 1815.

EDIT: And I've never heard that to be the official reason. Any Swiss citizens here that can complain to the gov if this turns out to be true?

really never heard of something more funny than that. I'll write a letter

Why did "they" always stay neutral, never making it big into history books?

PHA! Of course you mean besides slaughtering Habsburgs, defeating the number 1 military juggernaut in Europe, the Burgundians, getting independent from the Holy Roman Empire of the German nation, defeating the Swabians, invading Italy, mass slaughtering French, having a reputation of being unbeatable for 200 years, convincing the pope not to let himself being protected by anyone else than Swiss mercenaries, making kings of that age consider it impossible to win a battle without Swiss mercenaries, and when finally being closely defeated by a force superior in numbers and canons, still performing the first ordered retreat since antiquity...