In August 1812, Colonel John McPherson puchased 415 acres from William Marshall, son of James Marshall. McPherson was a substantial property owner and entrepreneur with strong ties to the growing industrial and transportation interests in the region. McPherson had purchased several land parcels in the Monocacy area during the first two decades of the nineteenth century, apparently with the goal of undertaking major industrial and transportation development. McPherson's son, John Jr., was also well-connected; he was married to Fanny Johnson, granddaughter of the first governor of Maryland and part of a family of major iron industrialists.
Colonel John McPherson died in 1829, leaving his son John, Jr. his extensive estate. In 1831, John McPherson, Jr. had the various land parcels resurveyed into a 1,111-acre tract that he called Araby. In all, the various parcels purchased by the McPhersons encompassed land that eventually became the Thomas, Worthington, Baker, and Lewis farms. In addition, John McPherson, Jr. became involved in merchant milling, constructing the Araby (Gambrill) Mill in 1830.
In spite of his extensive business ventures and inherited property, John McPherson, Jr. was deeply in debt by 1844, owing more than $72,000. This forced the sale and subdivision of Araby into several smaller parcels, which today form five of the six component properties at Monocacy National Battlefield.