Roger Quarles Mills, member of the United States House and Senate and Confederate army officer, was born on March 30, 1832, in Todd County, Kentucky, to Charles Henley and Tabitha Buckner (Daniel) Mills. After an academy education, he moved in 1849 to Jefferson, Texas, and in 1850 to Palestine. He soon received appointment to the staff of the state legislature. He was admitted to the bar in 1852 and became a lawyer at Corsicana. He later held local office and favored temperance. He wed Carolyn R. Jones, a planter's daughter and sister of John B. Jones, on January 7, 1855. They had a son and four daughters. During the 1850s Mills moved from the Whig party to the American party and then to the Democratic party. As a legislator representing Navarro County in 1859–60 he supported states' rights and frontier defense. Mills favored Breckinridge in the 1860 presidential election and then turned to secession. He enlisted as a private in Col. Elkanah Greer's Third Texas Cavalry, soon transferred to Col. Allison Nelson's Tenth Texas Infantry, and swiftly rose to the rank of lieutenant colonel. Late in 1862 he was promoted to colonel and given command of the regiment. He became a prisoner at Arkansas Post after the capture of the Tenth Texas on January 11, 1863, and spent time in Camp Chase, Ohio. After an exchange of prisoners later that spring, the Tenth Texas eventually became a part of James Deshler's brigade of Patrick Cleburne's division of the Army of Tennessee. At the battle of Chickamauga, September 19–20, 1863, Mills served as acting brigade commander when General Deshler was killed in action. He was twice wounded, first at Missionary Ridge on November 25, 1863, and then at the battle of Atlanta, July 22, 1864. He led a brigade at Chickamauga before suffering a wound at Chattanooga in late 1863. He served in the Atlanta campaign during 1864 until a wound hospitalized him.
In the late 1860s Mills became active as an attorney and member of the Southern Methodist Church. Elected as a representative to Congress on November 8, 1872, he spoke for the end of Reconstruction, frontier defense, and funds to expand rail lines and ports in Texas, while disagreeing with currency limitation. Mills, favoring individual freedom, helped defeat a state prohibition amendment during 1887. He opposed high tariffs and supported expanded trade in the 1880s. When he became House Ways and Means Committee chairman he developed the Mills Bill for reduced tariffs. Mills spoke frequently across the East and Midwest for the bill during the 1888 presidential election, but the Democrats met defeat. He then authored essays in Forum and North American Review about political topics. They included "The Gladstone and Blaine Controversy" in 1890 and "The Wilson Bill" in 1894. In 1891 Mills lost a contest for speaker of the House because interest in tariffs had declined and been replaced by silver coinage. The following year Democrats in the Texas legislature chose him for a seat in the United States Senate. He won reelection in 1893. There he favored reduced tariffs and the revolt in Cuba, but disagreed with acquisition of Hawaii. In 1898 he considered but decided against a reelection campaign. He retired from the Senate on March 3, 1899. The success of oil wells on his Corsicana property allowed him a secure retirement. He had received an honorary degree from Washington and Lee University in 1894. He was a Methodist and a Mason. He died in Corsicana on September 2, 1911, and was buried at Oakwood Cemetery in Corsicana.