He was known as L. Q. C. Lamar. Lucius Quintus Cincinnatus Lamar was born at his grandfathers' plantation, Fairfield, near Eatonton in Putnam County, Georgia, on 17 September 1825, into an aristocratic planter family. He was educated in nearby Milledgeville, and then attended Emory College and became a lawyer; he was elected to the Georgia state legislature for the 1853-54 session, but like many others during this time, he moved westward to Mississippi to make his fortune. He took up residence and opened a law practice in Oxford, Mississippi, and later became a faculty member at the University of Mississippi, a position he no doubt secured with the help of his father-in-law, Augustus Baldwin Longstreet, who was President of the University. During the Civil War, Lamar organized the 19th Mississippi regiment of volunteers and saw action against Union General George McClellan during his 1862 Peninsula campaign in Virginia. Lamar was appointed ambassador to Russia by Confederate States of America President Jefferson Davis, but he was never received by the Russian government since the Confederacy’s sovereignty was never recognized abroad. After his return from Europe in 1864, he served as a political spokesman for Davis and as a judge advocate in the military court and as acting aide to General James Longstreet, who was his father-in-law’s nephew.
Lamar returned to Mississippi after the war, where he resumed his law practice and position on the university faculty, directing the law department until 1870, the year Mississippi was readmitted to the Union. In 1872, Lamar was elected to Congress, Mississippi's first Democratic congressman since Radical Reconstruction. In his solitary role, he was in a position to lead the party to new goals, beginning with a carefully formulated southern program of sectional reconciliation, which he was able to present formally upon the death of Massachusetts Senator Charles Sumner, whose fervent abolitionist beliefs had been cause of much southern resentment prior to the war. With rhetorical brilliance Lamar championed Sumner’s call for amnesty for former Confederates, which quickly rang throughout the country and made Lamar famous.
Lamar’s political fortunes continued to rise, as the Mississippi legislature sent him to the United States Senate in 1877. With the election in 1884 of Grover Cleveland to the presidency (the first Democrat since before the Civil War), he became a cabinet member for three years. In 1888, Lamar became a member of the United States Supreme Court. As he had during his political career, he continued to rule in favor of economic nationalism and states right, opposing the enlargement of the national government's political power, particularly in the area of implied authority over civil rights. He died 23 January 1893 in Georgia.
—John B. Padgett

United States Senator, Congressman, Confederate Diplomat and United States Supreme Court Justice. ®1856
He was a student of the renowned Judge Augustus B. Longstreet ; L.Q.C. Lamar, Jr., married Longstreet's daughter, Virginia; followed A. B. Longstreet to Mississippi in 1849 when Longstreet assumed the presidency of the University of Mississippi; there, Lamar taught mathematics. L.Q.C. Lamar, Jr., moved to Covington, Ga., in 1852; Georgia House of Representatives, 1853; returned to Mississippi, 1855; U.S. House of Representatives 1857-1860; a member of the Mississippi Secession Convention, he drafted the Mississippi secession ordinance; Lt. Col., C.S.A., until 1862; Confederate diplomatic service from 1862, on special missions to England, France and Russia; member of the Mississippi constitutional conventions 1865, 1868, 1875, 1877 & 1881; professor of metaphysics, social science and law at the University of Mississippi; U.S. House of Representatives 1873-1877, where he was chairman of the Committee on Pacific Railroads; U.S. Senate 1876-1885, where he was chairman of the Committee on Interior and Insular Affairs, and the Committee on Railroads; U.S. Secretary of the Interior (President Grover Cleveland) 1885-1888; Associate Justice of the U.S. Supreme Court 1888-1893

Did he die in Vineville, Georgia?