Hi Don. I've just recently uncovered a William A. Mensch who was working on the farm of Adam Mensch, Marshall, Calhoun Co., MI in 1870. He is 22 which means he was born about 1848. He was not listed with the household in 1860 and I questioned whether he was Adam's son or simply a farm worker? Frank Mensch is also listed in 1870 as "works at farm", but I know who he belongs to.

I also found the marriage of a William A. Mensch to Mary E. Hona, 10/10/1871, Marshall, Calhoun Co., MI.

If this is your ancestor and we can connection, I can share genealogy back to the 1600's with you.