Slemons was born in Dresden, Tennessee on March 15, 1830. He attended Bethel College, studying law. Slemons moved to Arkansas in 1852 and was admitted to the bar in 1855 and practiced in Monticello, Arkansas. He was member of the Arkansas State convention in 1861. Following Southern Succession, Slemons entered the Confederate Army in July 1861 and served as colonel in Price’s Cavalry throughout the Civil War. He resumed the practice of law at wars end, and served as a district attorney from 1866 to 1868. Slemons was elected as a Democrat to the Forty-fourth, Forty-fifth, and Forty-sixth Congresses, serving from March 4, 1875 to March 3, 1881. He was not a candidate for renomination in 1880, but instead resumed the practice of his profession in Monticello. He became a county and probate judge of Drew County from 1903 to 1907 and was justice of the peace from 1908 to 1918; He died in Monticello on December 10, 1918.