From The Heretic Knowledge Vault
In story context, an old-fashioned, dilapidated "Dutch" windmill that plays an important role in getting the story line off and running. A group of Gewehr operatives have taken shelter there, and unwisely (terminally so), failed to cover their tracks. As a result, they're wiped out via time-ninja attack by Sara Amraphel, under the watchful eye of her mentor Warrel. This episode gives us a preview of just how nasty the Ensigerum are, and also of the fact that they've declared war on the Gewehr, although neither is totally clear from this episode; indeed, neither Gewehr nor Ensigerum are named yet.
We don't know exactly where this dead windmill is, but it's presumably somewhere in Veracia. It's the Gewehr's expansion into Veracia (from their home base in Farrel) that has sent the Ensigerum on the warpath -- well, that and a minor embarrassment in a professional context -- and so this combat must be occurring on Veracian soil. Lacking specifics, that's about the best we can do to locate it.
For more than you really wanted to know about windmills, check the Wikipedia article on the subject. It's apparent from this article that the windmill appearing in our story is quite large as windmills go, and is probably used for grinding grain -- or it used to be, before falling into disrepair and becoming a Gewehr hideout.