Peter GEIGER Bronze Plaque, Union co, PA

Looking for information on the bronze plaque placed by the tombstone of Peter Geiger in St Peter’s Reformed churchyard, Union county, PA.
It reads Peter Geiger 1 Regt Berks Co Militia Revolutionary War Nov 2, 1759 Sep 2 1843
Who might have placed it? Family member? Patriotic organization?
I have a .jpg of the tombstone and plaque that I would be glad to send upon request to aid in its identification.
The family name has also been spelled GEYER/GUYER, etc.

Peter died at Kelly Crossroads, Union co, PA. His wife was Anna Maria GEHRET.