Frederick County was established in 1743 from parts of Orange County, Virginia. At that time, "Old Frederick County" encompassed all or part of four counties in present-day Virginia — Shenandoah, Clarke, Warren, and Frederick. It also included five in present-day West Virginia — Hardy, Hampshire, Berkeley, Jefferson and Morgan. The Virginia Assembly named the new county for Frederick Louis, Prince of Wales. He was the oldest son of King George II of Great Britain.