Served as an officer in the Swedish, Hessian, French, and English armies. Immigrated to Wilmington, Delaware (1749). Lieutenant and fortifications engineer in a British regiment (1757-70). Surveyed a tract of land in the Crown Point district and resided there until he returned to England in 1769. Retired from army, appointed surveyor of the forests of North America at £300 per annum (1770), and reportedly drank himself to death.
Son of Erik Benzelius the younger, Archbishop of Uppsala, and his wife Anna Svedberg. Educated at Lund. Married Rebecka Tranberg, daughter of Swedish pastor Peter Tranberg of Holy Trinity Church, Wilmington (1752); one daughter, who ultimately settled in Quebec.