I'm talking about historical use of these letters in Latin.
But if you've seen middle and early modern English text that hasn't been sanitized for modern readers, you will see a lot of stuff. You'll see W written as uu. You'll see lots of Vs and Us trading places, in places we no longer put them.
And eg. I kind of suspect the UK pronunciation of lieutenant, where u is /f/, has roots in it being /v/.