I have a census index for 1870, and it contains a Christian Dahmer with the following info:
Age: 40, Sex: M, Race: W, Birthplace: HDAR, State: IL,
County: Monroe, Locale: Columbia, Series: M593,
Roll: 261, Page: 412
There are some more Dahmers with a birthplace of HDAR. Let me know if you are interested and I will send you the information.