When Gregory P. Wilson began researching his family history, he never expected to uncover an ancestor as unique and fascinating as Jonathan Roberts. A devout Quaker, Roberts wore many hats throughout his life. He was a farmer, surveyor, husband, and father. He also was a firm abolitionist, the Civil War's Quaker scout and sheriff in northern Virginia.

Roberts's noncombatant military service began shortly after his secessionist neighbors tried to kill him for his political and antislavery views. Fleeing his Fairfax County home after Confederate General P.G.T. Beauregard ordered his...