Samuel Marshall's private banking office was joined by Charles F. Ilsley.

The evidence

• “In 1847, the foundation of the present well-known firm of Marshall & Ilsley was laid by Samuel Marshall, who, in that year, opened a private banking office in Milwaukee, and was joined in 1849 by Charles F. Ilsley.”

  1879-history-of-rock-county/04-wisconsin-railroads-commerce-health-statistics.md, PDF p. 188 / book p. 192

  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