Why note B is marked with H in Scandinavia and Germany?

Question

At least in Scandinavia and Germany two notes are marked differently than in most other countries: - B -> H - B♭ -> B. I have heard that this is due to mistake in interpreting messy sheet notes, as ♭ is close to b and ♯ resembles H. The story goes that a musical scholar thought that the note is H and when B was later encountered, it was deduced that it must be a special name for H flat as H was already established in its place. But this may be an urban (or actually historical) legend. How did this difference come to be?

Answer 1

I always heard that it came out of Musica Ficta. When playing in a mode focused around F, musicians knew to just play every B as a Bb to avoid the tritone. But it wasn't written, just KNOWN. And most modes didn't really use a B natural anyway, so when expanding the range and function of modes into scales, we already used the letter B for Bb, so it became an H.

Although I'm an American. I'd love to hear from a German musician why this happened, as it's taught there.