I'm a little late in responding to your message, but a lot has happened in my world.
I have a copy of a newspaper clipping which is titled "Mortuary Record", and appears to be an obituary of Nicholas. This was given to me by my mother, who is the daughter of Seth W. Eisenbise.
This newspaper article highlights the life of Nicholas, and spends some time detailing his association with the First Brethran Church. I would believe that the military gravesite you mention must surely be his final resting place.
In this article it also mentions his brother George W. Eisenbise of Cherry Grove. Thought you might like to know that.
Let me know if I can provide any other information.