That was an interesting read. The province flag where peat was harvested in the Netherlands has a tiny castle:

But that province does not have any castles! So it is a reference to the fact that the peat province was controlled by another province which does have castles.
I think I've gone down a peat rabbit hole. Since reading your comment I looked up peat in the Netherlands. Didn't realize how large a role peat played in the Netherlands history, largely because there weren't a lot of trees. Here are two interesting articles I found:
http://www.peatsociety.org/sites/default/files/Zeeuw.pdf
http://varletfamily.pbworks.com/w/page/8500473/The%20Peat%20Industry
Welcome to my rabbit hole :)
My great grand parents were peat harvesters so welcome to my great grand parents life :P
That is fascinating. I can't believe how rich the subject of peat is. Every time I open a door, I discover something new.
I'm looking into turf houses now. Amazingly, fits right into a blog I've been working on for more than a week. No, not a peat blog. Unrelated. Or at least I thought it was :)