I have found a tombstone of a FRIEDERICH KANNENBERG in a little cemetary about 7 miles east of WATERLOO, WISCONSIN. It looks like an expensive stone and is entirely in German, not all of which I understand( the word "gelreu"). It contains a beatiful poem/prayer.
It appears like this:

FRIEDERICH
KANNENBERG
geb. Octbr. 10
1799
gest. Sept. 28
1864.

Du hast Dein Tagenwerk
gelreu vollendet,
Und weinend stehen wir
an Deiner Gruft,
O ruhe sanft, Dein Leben
ist geendet,
Bis Dich der Herr zur
Auferstehang ruft.

English translation:
You have (adverb?) accomplished your daily work,
and weepingly we stand on your crypt,
Oh gentle calmness,
Your life is ended,
Until [You the Lord] invokes
resurrection.

I have a picture I can email if anyone is interested.