Martin B. Key was born around 1829, probably in Tennessee. He married Violet Puckett on February 8, 1853, and they had at least five children, including: William, born around 1853; John, born around 1854; Jesse, born around 1856; and David, born around 1859. They lived in Spring Creek, Tennessee, and he worked as a farmer. By 1860, he owned $3,000 of real estate and $24,000 of personal property. A decade later, he owned $5,000 of real estate and $2,500 of personal property. He died near Claybrook, Tennessee, on August 20, 1873.