Here's the genealogical proof that the John Bryant found in Tishomingo MS in the 1840 and 1850 census was John Bryant III, son of John Bryant, Jr. b. 1754 and Judith Winfrey. It was later substantiated by DNA.
1. Parallel Migration Paths of two John’s – There are two applications for bounty land for service in the war of 1812 made by a John Bryant in Tippah Mississippi in 1851 and in Tishomingo MS in 1855. In these two documents he states that:
a. He entered the service for the War of 1812 from Adair KY in 1812
b. He enlisted [with Randolph Bryant, proven son of John Jr. and Judith] in the 7th Regiment Kentucky Militia in the Company commanded by John W. Shirley.
c. He was discharged to Adair KY in 1813
d. Sometime later his papers were burned in a fire in Lincoln County TN.
This placed him in Adair County KY prior to 1812 and Lincoln County TN sometime after 1813. This is parallel to the migration of John Bryant Jr., who lived in Adair in the early 1800's and in Lincoln TN after 1813.
2. Proximity of two John’s in 1820, designation as John Bryant 3rd – Additionally, in the 1820 census, Randolph Bryant was living just 8 households away and John Bryant Jr., husband of Judith Winfrey, was 11 households away. Also, in 1820 there was a notation by the younger John Bryant’s name which said “3rd”. This fits because his father and grandfather were both named "John."
3. Connection to Priscilla Shelton identifies John in 1820 and 1830 census – Other trees state that John Bryant in Tishomingo MS was married to Letha Shelton, daughter of Priscilla Shelton. This is supported by the fact that in 1850, Litha Bryant age 50 was in John Bryant’s household in Tishomingo. And in 1860, Priscilla Shelton (96) was living with Lettie Bryant, widow. In both the 1820 and 1830 censuses in Lincoln County TN, John Bryant was living next door or two doors down from Priscilla Shelton. Even though his age was off in the 1830 census, his proximity to Priscilla Shelton and the consistency of the ages of the rest of his household lead to the conclusion that this is the same John Bryant that is found in Tishomingo in 1840 and 1850.
4. Confirmation by descendants –Stories handed down by children of Harmon Bryant and William Price Bryant/Hetty Bryant state that their ancestor saw Cornwallis surrender and was from Middle Tennessee and Jackson Co, AL. This matches John Jr.
5. Tight Web of Family Connections - These are detailed here.
6. Naming similarities –
a. John Bryant of Tishomingo had a daughter "Hetty," who married "William Price Bryant" who was probably a cousin of Hetty's. Meanwhile, Anthony Bryant named a son "William Price Bryant."
b. There was an Anthony Bryant in Tippah MS, a son of John III. Anthony was also the name of John Jr’s brother.
c. John’s niece, Priscilla Bryant Parish, named a son Giles Preston Parish. Randolph Bryant, proven son of John Jr., had a son and a grandson named John Preston Bryant.
d. William Price and Hetty Bryant had a son named "Elisha." Austin Bryant also had a son named "Elisha." William Bryant, son of John Jr., had a son named "Elisha."