Sussex County covers 515 square miles, was formed in 1753 from Surry, and was named for an English county; Cornwallis passed through it in 1781. Southampton County covers 604 square miles, was formed in 1748 from Isle of Wight and Nansemond, and took its name from a locality originally named for the Earl of Southampton, who was active in the first settlement; General William Mahone was born there.