John F. Hardin represented Newton County in the Georgia State Legislature from 1868 to 1870. Rockdale County was created on October 18, 1870 by act of the Georgia General Assembly and received its name from Rockdale Baptist Church, which was named after the granite strata that rests under the county's red clay top soil. A bill introduced by John F. Hardin and John Harris carved Rockdale out of the northern portion of Newton County; part of Rockdale County also came from neighboring Henry, Walton, Gwinnett, and DeKalb counties. Rockdale's only incorporated town and urban center, Conyers, became the county seat.

National Park Service, US Civil War Soldiers, 1861-65 database record: John F. Harden, Confederate, 14th Regiment, Georgia Infantry, Company G, Private.

John F. Hardin was married three times:
1st on 13 Mar 1827 in Henry County, GA to Edythe/Edetha Harper
2nd on 21 Jan 1864 in Newton County, GA to Mary W. Overbay
3rd on 15 Dec 1869 in Newton County, GA to Ann Elizabeth Fee

The Atlanta Constitution, 11 Sep 1883, pg 8:
Colonel Hamlin's Funeral
The funeral of Colonel John F. Hamlin was witnessed by many friends and relatives last Sunday evening at Conyers. Mr. Hamlin was one of Rockdale county's oldest and most respected citizens. He was a consistent member of the Baptist church for near half a century, and was highly esteemed as a Christian and a citizen by all who knew him. He had five sons who defended their county in the late war, two of whom gave up their lives on the battlefield, and the other three witnessed the death of their father.

The Atlanta Constitution, 12 Sep 1883, pg 8:
In the funeral notice of Colonel John F. Hardin, of Rockdale county, published yesterday, the name was incorrectly printed Hamlin.