Northumberland County probably was named for the English county. It was formed about 1645 from the district of Chickacoan, the early-seventeenth-century name for the region between the Potomac and the Rappahannock rivers.

Throughout the Civil War, the principal responsibility for Virginia's indigent soldiers' families lay with the locality. The Virginia State Convention in 1861 gave the responsibility entirely to counties and incorporated towns and authorized whatever actions had already been taken. Acts of Assembly in 1862 and 1863 expanded the localities' powers to provide for their needy, and in 1863 some minimal state assistance was added in. At first relief was provided as money, but as the monetary system collapsed, relief was distributed in kind. Agents of the court maintained lists of eligible families, gathered goods for distribution and paid for them, and impressed supplies if necessary. Virginia was unique amongst the southern states in that it assigned the provisioning of needy families almost solely to the locality.