It's a unit marking for a cavalry regiment. 2nd Eskadron, Reiter Regiment 3, weapon 18.
Sent from my Pixel 5 using Tapatalk
Reiter Regiment 3 was apparently based in Göttingen.Thanks for that information. I was using the markings section of Walter's bayonet book as my guide and that was clearly not where I should have been looking. Any idea where they were located?