October 1, 1840
Benjamin Brown arrived in Beloit with his wife (married May 14, 1840) and her daughter Lucy; the 1908 history also says his father first came to Beloit in 1840 and that Brown arrived in October.
BeloitGrade A · 1 independent source
The evidence
“Leland, and started west, aiming to settle in Burlington, la. Friends, however, induced him to come to Beloit, where he arrived with wife and little step daughter, Lucy, October 1, 1840.”
1908-brown-rock-county/34e-biographical-5.md, Vol. 2, PDF p. 592 / book p. 1076
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