Fergus Kyle was born on September 6, 1834, in Hinds County, Mississippi, to Claiborne Kyle and Lucy Bugg. His father was a farmer who owned $4,075 of real estate and $26,010 of personal property in 1860, including at least one slave. The family moved to Texas in 1844, settling in Hinds County six years later. He attended Thrall’s Academy in Austin, Texas, and he married Anna Elizabeth Moore in 1860. They had at least eight children: Mary, born around 1865; Aline, born around 1869; Sidney, born around 1869; Albert, born around 1874; Thomas, born around 1877; Rose, born around 1879; and Emma, born around 1882. He probably enlisted in the Confederate army in September 1861, mustering in as a private in Company K of the 8th Texas Cavalry. He was promoted to captain after the Battle of Shiloh, and he eventually became an aide to General Benjamin Cheatham.
After the war, Kyle returned to Hays County, Texas, where he worked as a farmer. He was elected to the Texas legislature as a Democrat in 1870, and he served as sergeant-at-arms of the Texas senate from 1881 to 1884. He returned to the Texas house of representatives in 1901, and he died on May 19, 1906.