The marker text reads as follows: "Founded in 1786 by Charles Washington, brother of the President. Here John Brown was tried and convicted of treason. Home of W.L. Wilson, Postmaster General, 1896, who here started the first rural free delivery in America."
Additional information is available from Wikipedia:
Charles Town is a city in Jefferson County, West Virginia USA. The population was 2,907 at the 2000 census. Due to its similar name, travelers have sometimes confused this city with the state's capital, Charleston. It is the county seat of Jefferson County. Charles Town's 2006 Census population estimate is 3,869.
Charles Washington, the founder of Charles Town, was born in Hunting Creek, now Fairfax County, Virginia on May 2, 1738. He was the youngest full brother of George Washington. He came to present Jefferson County between April and October 1780.
The home of Charles Washington, Happy Retreat, was erected in 1780. In 1786, on 80 acres (320,000 m²) of his adjoining land, Charles laid out the streets of Charles Town, naming many of them after his brothers and one after his wife, Mildred. He donated the four corner lots at the intersection of George and Washington Streets for public buildings of the town and county, provided the town become the seat of the county separated from Berkeley County. Jefferson County was formed in 1801 as he anticipated. The county court house stands on one of these lots, as did the jail until 1919 when it was demolished to be replaced by the post office.
Charles Washington died sometime between July and September, 1799, only a short while before the death of his brother, George. Charles' and his wife Mildred's grave sites near Evitts Run have recently been located and surrounded by a stone wall.
In 2006, a non-profit corporation, called the Friends of Happy Retreat, Inc. (FOHR), purchased an option to buy the property outright. The goal of this group is to see Happy Retreat preserved as a national historic treasure while at the same time contributing to the public’s appreciation of the arts, local culture, and the rich history of the Washington family and the Eastern Panhandle of West Virginia.