John F. Avery was born around 1841 in Georgia to William and Susan Avery. His father was a farmer who owned $525 of real estate in 1850. The family moved to Gadsden County, Florida, in the 1840s, and by 1860, they were living in Jackson County, Florida.
He enlisted in the Confederate army on May 5, 1863, and he mustered in as a private in Company F of the 11th Florida Infantry later that day. According to his service records, he was 5 feet, 6 inches tall, with light hair and blue eyes. The regiment took part in the Overland Campaign and the Appomattox campaign. He was wounded at Weldon Railroad on August 21, 1864, and he received a furlough soon afterward. He eventually recovered and rejoined the regiment, and he received his parole in Lynchburg, Virginia, on April 10, 1865. He died sometime after the war.