Yeah, the most unusual part about FW isn't that he was brutal to his kids, it's that he was brutal to his kids for doing what most other noble/royal parents wanted their kids to do.

Normal kid: *doesn't want to study Latin*
Normal kid: *gets beaten*
Fritz: *eager to study Latin*
Fritz: *gets beaten*
Most parents: *would die to have bb!Fritz*

Btw, cahn, I was rereading Zenna Henderson's short stories this week, and watching even the nicest teachers paddle the kids for misbehaving in the 1950s was a definite moment of "Oh, right, you could *do* that then."