In 1792, prior to purchasing the property, George Riley married Sarah Wilson .... At the time of their marriage, Sarah had inherited land from her father’s estate. Although historical documents identify George Riley as a planter, he also served as a Montgomery County Commissioner and as a member of the House of Delegates .... Following Sarah’s untimely death in October 1810, George married Mary Richards. George died five years later, leaving Mary with their three young girls. In 1818, she married Arnold Thomas Windsor. ....
By the time of George Riley’s death in 1815, Isaac Riley, a younger brother, is believed to have been residing on the property. Isaac was the executor of George Riley’s will, and apparently he continued to operate the farm in that capacity after his older brother’s passing. It is evident that Isaac Riley remained on the property until his death in 1850.
Even before he had any claim to the land, Isaac did have title to enslaved workers. Before 1818, while still a bachelor, Riley family documents and census records indicate that he resided with a sister and several slaves .... Census records from the 1820s indicate that the plantation had at least twenty enslaved workers, plus additional enslaved children. The produce, which included wheat, oats, barley, potatoes, corn, tobacco, hay, fruit, and butter, was sold at the local markets in Washington and Georgetown. Animals on the plantation included sheep, pigs, and chickens.
Josiah Henson ... was separated from his mother at age five and was sold to [Rockville] tavern owner, Adam Robb, who lived approximately four miles from the Riley plantation. When he fell seriously ill, arrangements were made by the tavern owner to reunite the young Josiah with his mother[, who was owned by Isaac Riley]. Henson was approximately six years old when he was reunited with his mother; for the next thirty years he was enslaved on the Riley plantation.

