June 30, 1832
General Atkinson's army, including Private Abraham Lincoln, entered Rock county, marched through the deserted Turtle village (now Beloit), and encamped — the first recorded visit of white men to this locality.
BeloitGrade A · 1 independent source
The evidence
“The tirst recorded visit of white men to this locality was that made by soldiers of the Black Hawk War under General Atkinson, including Private Abraham Lincoln, June 30, 1832. On that day they marched through this Turtle village, then deserted by its Indian inhabitants, and camped during the afternoon on the prairie about two miles north.”
1908-brown-rock-county/06-history-of-beloit.md, Vol. 1, PDF p. 145 / book p. 130
Brown, William Fiske, editor. Rock County, Wisconsin: A New History of Its Cities, Villages, Towns, Citizens and Varied Interests, from the Earliest Times, Up to Date. Chicago: C. F. Cooper & Co., 1908. 2 vols. archive.org/details/rockcountywiscon01brow, archive.org/details/rockcountywiscon02brow.
Grade A: Found on a page of one of our sources