I have some information about August Marquardt. Are you still looking for more information?
I am a great great granddaughter of Emelia (Amelia) Marquardt and her husband, Robert Truax, who were in Jenny (Merrill), Wisconsin in the 1870 and later censuses. I recently traveled to Merrill. August and Fredricke Marquardt are buried in the cemetery there. August died in 1915, Fredricke in 1903.