Rockingham County was established in 1778 from Augusta County. Harrisonburg was named as the county seat and incorporated as a town in 1780. Harrisonburg was incorporated as a city in 1916 and separated from Rockingham County (all cities in Virginia are independent of any county), but it remains the county seat. [citation needed] The county is named for Charles Watson-Wentworth, 2nd Marquess of Rockingham, a British statesman (1730â1782).