Clark County, with an area of 171 square miles, was formed in 1836 from Frederick and later added to from Warren, and was named for George Rogers Clark, conqueror of the northwest; Lord Fairfax and General Daniel Morgan, a revolutionary hero, lived in this county. Fauquier County, with an area of 666 square miles, was formed in 1759 from Prince William and named for Francis Fauquier, governor of Virginia from 1758 to 1768; Chief Justice John Marshall was born in this county.