John Fairfield Libby was born on September 19, 1842, in Carthage, Maine, to Hiram and Naomi Libby. His father was a farmer who owned $1,000 of real estate and $500 of personal property by 1860. The family lived in Carthage until the 1850s, when they moved to Dixfield, Maine. By 1860, he was working as a farm laborer.
He enlisted in the Union army on September 29, 1862, and he mustered in as a private in Company F of the 23rd Maine Infantry. The regiment served on guard duty along the Potomac River. He was promoted to corporal in January 1863, and he mustered out on July 15, 1863.
He returned to Carthage after leaving the army, and he married Ellen E. Newman. They had at least two children: Charles, born around 1868; and Ida, born around 1869. He worked as a blacksmith, and by 1870, he owned $600 of real estate and $400 of personal property. His wife probably died by the early 1880s, and he married Mary A. Barrett on December 24, 1885.
He supported the Republican Party, and he served several terms in the state legislature. He also served as a justice of the peace and a town selectman. By the late 1880s, he was suffering from chronic diarrhea. He applied for a federal pension in January 1889 and eventually received one. By 1890, he was suffering from chronic diarrhea. According to a local writer, he “had been ill for several years, as the result of exposure in the army during the Civil War, but had been able with the assistance of his wife to engage in trade.” He died on September 3, 1897, “from a disease which had long puzzled local physicians.”