I have a gggrandfather named Robert Helmer born about 1824 in either NY or MA died ? married first to Lucy Ormun then to Ellen A. ??. He lived in Michigan. The daughter from Lucy, Mary Eleanora married my ggrandfather, Dr. Theodore Cole of Michigan. He lived in Dorr but died in Lansing. I have seen where there is a Robert W. Helmer in the 7th Tennessee Cavalary and my ggrandmother (Mary Eleanora) died in Nashville, TN. No idea how she ended up there as I do not show any family in Tenn unless the Helmers moved to Tenn after the Civil War. If he fought for the CSA it might have been a prudent move as I am sure he made enemies in MI by fighting for the South.
Would be interested to see what you have.

Robert Cole
Major, USA, Ret
Enterprise, AL