I have found August and Catharina in the 1870 census for Manitowoc Co., Schleswig Township, WI--
August was 32, so born 1838, in Prussia. He was a carpenter.
Catharina was 35, born in Prussia, and they had a son, Gustav who was 7, so born 1863 in Wisconsin.
The 1860 census (same locality) lists a family noted as "Lee" on one page and "See" on the next, but I think these are the Sys: (all born in Prussia except the last)
Lee, Abraham 48 M Farmer
August 24 M Carpenter and joiner
William 21 M
Gustav 15 M
Charles 14 M
See, August 15 m Prussia
Catherine 5 f Wisconsin
This record was made 4 Sep 1860, a couple of months before August would have married Catharine. There are obviously some censustaker's errors here but I think this is the family.
Anyway, if any of this rings any bells, I would like to know more, share, etc.