My great grandfather, William Henry Whitmarsh came from Canada to LaSalle Illinois in the mid 1800s. He was horse breeder, and he and my great grandmother raised their family during the 1860s seventies and eighties.Their daughter, Katherine, traced the Whitmarsh name back to Sussex England, where our ancestors raised cattle - though I don't know how long it was from Sussex to Canada to Ilinois (her work is not available so far as we know). Have you come across a William Henry Whitmarsh in your research? My guess is that he was born in the 1820s or so. My great grandmother being born in 1833.