Westmoreland County was named for the English county. It was formed from Northumberland County in 1653, and part of King George County was added in 1777.

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.