James B. Davenport was born on February 24, 1819, to John Davenport and Margaret McNew. He moved to Missouri sometime in the 1830s, and he married Lethe Harrison there around 1838. They had at least three children: Margaret, born around 1838; William, born around 1840; and Samuel, born around 1843. The family moved to Texas in the 1840s. By 1850, Davenport was working as a farmer in Henderson County, Texas, and he owned $500 of real estate. He moved to Uvalde County, Texas, a few years later and became Chief Justice of the county. By 1860, he was working as a stock raiser, and he owned $2,500 of real estate and $5,000 of personal property. He sided with the Confederacy during the Civil War, and on September 21, 1863, he enlisted as a 2nd lieutenant in the Uvalde County militia. He worked as a farmer after the war, and he moved to Bandera County, Texas, sometime before 1880. His wife Lether died in the early 1880s, and he married Jane Maria Lewis in Bandera County on June 23, 1884. Their son James was born on October 11, 1886. He died in Bandera County on November 30, 1892.