Gavin was a corporal in Captain Daniel Conyers company of Marion's Brigade.

Gavin married a cousin twice. He first married Esther Jane Witherspoon in 1774. She was a first cousin as both are descended from John and Janet Witherspoon. He second married his first cousin once removed, Ann Witherspoon. They too are both descended from John and Janet Witherspoon.

-Witherspoon, Joseph B. The History and Genealogy of the Witherspoon Family (1400-1987). Fort Worth, Tex: Miran Publishers, 1988. Print. p. 96. L10.