David Thomson's eldest son, Manlius Valerius Thomson, was a man of distinction. Born 13 Aug 1802, in Scott County, Kentucky, he married Mary Ann Thomson at Georgetown and there passed away 22 Jul 1850. He was president of Georgetown College in Kentucky and was also lieutenant governor of the state. A few additional facts regarding Manlius Valerius were gleaned from the Encyclopedia of the history of Missouri: A Compendium of History and Biography for Ready Reference edited by Howard Louis Conard (published 1901): He was educated at Transylvania University in Lexington, Kentucky, where he graduated with first honors. After his graduation from college he studied law, was admitted to the bar and opened a law office at Georgetown, Kentucky. His ripe scholarship and executive ability caused him to be made president of the Baptist College at Georgetown, and he held that position for a number of years. He took much interest in politics, and for many years was in close touch with the great leaders of the Whig party in Kentucky, including Henry Clay. A letter written him by Clay 29 Aug 1849, concerning the Mississippi debt, advised him to go to London to look after this matter, and closed with these words: "I authorize you to make any reference to my name in support of your views which may be calculated to secure their success. This is due to the high opinion I entertain of your honor, probity and established character. I am, your friend and obedient servant, Henry Clay."

In 1840 Manlius was elected Lieutenant Governor of Kentucky, with Governor Letcher, and filled that office until the close of his term of four years. At the outbreak of the war with Mexico he was commissioned colonel of the Third Regiment of Kentucky Volunteers and served in that capacity until the close of the war, participating in the battle of Buena Vista and other engagements which preceded the fall of the City of Mexico. While campaigning in that country his health became seriously impaired and he died shortly after his return to the United States. He was buried in the college campus at Georgetown, where a monument, suitably inscribed, has been erected to his memory. The inscription on the east side of the monument is as follows: "Col. Manlius Valerius, son of Gen. David Thomson: Born in Scott county, Kentucky , August 13, 1802. Died in Georgetown, Ky., July 21, 1850." On the north side of the monument is the inscription: "A graduate of Transylvania University; a lawyer of distinguished ability; elected on two occasions a Presidential Elector and voted as such for Henry Clay and President Taylor; elected Lieutenant-Governor in 1840 by an unprecedented majority ; colonel of the Third Regiment of Kentucky Volunteers in the war with Mexico." The west side of the monument bears this inscription: "In peace and in war, in public and in private life, he was eminent for those virtues that give grace and honor to whatever station he was called to fill. Beloved in all the domestic relations, acting well his part in life, he died in the meridian of his days. The State mourned the loss of one of the most distinguished of her native sons, and society sorrowed over the departure of one of its brighest ornaments."