I recently learned that my grandfather was, while assigned to the Prussian Army, Feldartillerie Regt. Nr. 43, 3. Batterie, was engaged in a battle along the Hermannstellung. From his Militarpass I have the following brief entry:
28.10.18 Fighting before and in Hermannstellung
A book I found ('Over There') referred to the Hermannstellung as 'Germany's last defense'...I am hoping someone on the GWF can direct me to where I can read more about the Hermannstellung, preferably in English.
I found the book "Battlefields of the World War" by Douglas Wilson Johnson, which had the following to say about the Hermannstellung:

Any information would be greatly appreciated. The anniversary of that battle is coming up later this month and I am hoping I will know a bit more about it before the date passes. I tried this post in The Western Front section but have had no luck there since the 1st, and just hoping a mention here will lead to some suggestions.
-Daniel