February 1848
A farm of seventy-three acres in Rock County was purchased.
Rock CountyGrade A · 1 independent source
The evidence
“Koshkonong ; born in Prussia Oct. 15, 1845; son of Garland Wilmena (Schmidt); came to America April 23, 1872, and settled at Ft. Atliinson, Jefferson Co; bought his farm of seventy-three acres in Rock Co., February, 1848. Married, March 12, 1872, Mary Waungerman ; they have four children — Carl, William, Fritz, Otto.”
1879-history-of-rock-county/26-bios-la-prairie.md, PDF p. 829 / book p. 833
Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.
Grade A: Found on a page of one of our sources