Both are found in the 1860 Census in McKinny TX in the homes of two Wilson/Willson families from TN. Robert joined Captain Throckmorton's company of Texas Rangers in June 1861, which returned from three months fighting Indians in your neighborhood and in mass became Company K, 6th Texas Cavalry Regiment in Sep 1851.
These two had many variations of Nolan during their enlistment. Nolan/Noland/Nolin/Nowlin/Nolen?Nowland, etc. Ether they could not spell or the First Sargeants of Companies D, K, and I of the 6th were illerate. Company I of the 6th was detached and served with Ras Stirman's Sharpshooter Regiment at Corinth II and Hatchie Bridge. Robert was capture at Hatchie Bridge with a broken Arm. He was parolled about two weeks later. Probably was well enough to ride on the famous Holly Springs Raid. Both brothers were on Paroll records in 1865, but I am not sure that they were there. Neither went back to Texas.