Robert Thomas Jones and several relatives served in the Tennessee Infantry during the Mexican-American War of 1846-1848. According to the Mexican War records for Tennessee on Fold3.com, Robert served in Company G, 5th Tennessee Infantry. His son, Robert Thomas Jr, also served in the 5th Infantry. The 5th was commanded by Col. George McClellan.
Robert Sr. mustered into service in Knoxville, Tennessee on 10 November 1847. He appeared on the muster roll from 10 November 1847 to 29 February 1848, on the roll for March and April 1848. He mustered out on 20 July 1848 in Memphis, Tennessee. The roll shows that he was last paid $21 for clothing through 30 April 1848.
Robert Jr. appeared on the roll as Thomas Jr., age 20. He also mustered in with the 5th Infantry in Knoxville on 10 November 1847. He accidentally drowned rowing through Muscle Shoals, Alabama on 17 December 1847.
I am still researching the service of the 5th Infantry during the War. I'd be interested to know if the company arrived in Mexico. There are other Jones names in the 5th Infantry, some of these could have been relatives of Robert Thomas Jones Sr & Jr.