William Johnson Jr. was born on December 27, 1771, in St. James Goose Creek Parish near Charleston, South Carolina. He was the son of William Johnson Sr., a prosperous blacksmith and revolutionary activist, and Sarah Nightingale Johnson. Although the elder Johnson worked in a mechanical trade rather than belonging to the Lowcountry planter aristocracy, his business success and political engagement placed the family within Charleston’s energetic urban middle rank. Both parents supported resistance to British rule, and their commitments profoundly disrupted William’s childhood.

During the Revolution, William Johnson Sr. worked alongside Christopher Gadsden and other Charleston Patriots. British authorities regarded him as a dangerous rebel. After Charleston fell in 1780, the elder Johnson was arrested and sent into confinement at St. Augustine in British East Florida. Sarah Johnson fled with her children, and the younger William spent part of the war away from South Carolina. Accounts differ on whether the family’s refuge should be described chiefly as Philadelphia or New York, but the central fact is clear: imprisonment and exile made the Revolution a personal childhood experience rather than an abstract political event.

After the war, the family returned to Charleston, where Johnson attended grammar school. He entered the College of New Jersey, now Princeton University, during the 1780s and graduated in 1790 at the head of his class. His studies emphasized classics, mathematics, history, moral philosophy, and rhetoric. The experience broadened the education of a young man whose earliest political lessons had come from occupation, displacement, and his father’s resistance.

Johnson returned to Charleston and read law under Charles Cotesworth Pinckney, one of South Carolina’s most prominent attorneys and statesmen. He was admitted to the bar in 1793. In 1794 he married Sarah Bennett, sister of the future governor Thomas Bennett Jr., and won election to the South Carolina House of Representatives. Admission to the bar, marriage, and election together marked his passage from a revolutionary household and demanding education into the professional and political life that eventually carried him to the United States Supreme Court.