Charles Buck I was born about 1710 in York County and died in 1771 in the Shenandoah Valley. He first moved from York County into Westmoreland County, but after a short stay there he received a bequest from his uncle Joseph which he used to buy land in the Shenandoah Valley about 1735. Charles prospered there, and became a large landowner near what is now Front Royal, VA. He was a Vestryman of Frederick Parish, Lieutenant of Militia, Trustee for the town of Strasburg, Overseer of Roads, and otherwise active and influential in county affairs.
Charles Buck I married Ann Sorrell Earle in 1747 in Earle Family Chapel, Muddy Run, VA. Ann Sorrell Earle was born in 1728 and died in 1749 shortly after the birth of her daughter Mary who also died. She was the daughter of Major Samuel Earle, a pioneer leader in the valley who was the first delegate from Frederick County to the Virginia House of Burgesses in 1744. Charles and Ann had two children: John and Mary.
After the death of his first wife, Ann Sorrell Earle, Charles BUCK I married Letitia Sorrell in 1749. Letitia was the widow of (1) Ambrose Callis and (2) John Wilcox. She was also the aunt of Ann Sorrell Earle, the first wife of Charles Buck I. Her son Thomas wrote of her "She was a strict moralist, and instilled into my mind a great reverence for the Supreme Being". She had children by her previous marriages; perhaps as many as three sons and five daughters. Charles Buck I and Letitia Sorrell had two sons: Charles (II) and Thomas (V).