Robert Johnson (February 22, 1834 – April 22, 1869) was the fourth-born child of Andrew Johnson and Eliza McCardle, a lawyer by profession, one-term Tennessee state legislator, Union Army cavalry officer during the American Civil War, and Secretary to the President of the United States. Johnson suffered from severe and chronic alcohol dependence. He died by overdose of alcohol and laudanum in the family home in Greeneville, Tennessee, six weeks after the end of President Johnson's term in office.
Early life
Robert Johnson, called Bob, was born in the family's Water Street house in Greeneville, the county seat of Greene County, Tennessee. He is said to have briefly studied at Franklin College in Nashville during the winter of 1850–51, but within short order returned home "for unknown reasons." During this time period he also apparently experienced some hemorrhaging of the lungs, possibly consequent to a tuberculosis infection. Johnson was a lawyer by profession, first licensed in 1856, having studied under an attorney named Robert McFarland. However, according to one contemporary newspaper account of his life, he was "never distinguished by his father's strong characteristics" in this profession. Robert and his brother Charles Johnson also managed their father's business affairs and real estate when Andrew Johnson was away from Tennessee. Early in his life, Robert Johnson had "seemed to be a responsible young adult, one upon whom his father depended for a variety of things." He attended the 1856 Democratic National Convention.Johnson served in the 33rd General Assembly of the Tennessee state legislature, for the term of 1859–1861, representing the "floating district" of Greene, Hancock, Hawkins, and Jefferson counties. According to the newspaper of dedicated Andy Johnson hater Parson Brownlow, "It is said that a principal object in trying to get Bob Johnson into the Legislature is to nominate, through that body, his daddy for the Presidency." Robert Johnson attended the 1860 Democratic National Convention in Charleston, South Carolina. Andrew Johnson was the only member of the U.S. Senate from a secessionist state who stayed loyal to the federal government; like his father, Robert Johnson was a "consistent, fearless and uncompromising Southern Unionist," and he made a notable speech at a courthouse in Nashville in defense of "Union, the Constitution and the Laws" just before the Tennessee ordinance of secession. In June 1861, he was a delegate from Greene County to the pro-Union East Tennessee Convention. As a vocal Southern Unionist, Johnson (along with his brothers, and his brothers-in-law David T. Patterson and Dan Stover) was in genuine danger in Tennessee in 1861—correspondents informed Andrew Johnson, safe in Washington, that Robert Johnson was under threat of arrest and even hanging. During the early months of the American Civil War, Johnson was hidden from Confederates by a Greeneville farmer named Robert Carter, and may have also sheltered with one or more of the Union-aligned guerrilla bands working in the mountains. Bob Johnson later told a group of fellow Union-aligned East Tennesseans of having "scouted for months in the mountains of his native country, hunted from place to place, like a felon." On February 27, 1862, it was reported that he had arrived at a Union camp at Camp Garber on Flat Lick, Kentucky, after a two-week-long journey through parts of Tennessee still controlled by Confederates.
Union Army
Robert Johnson joined the Union Army at Camp Dennison (near Cincinnati, Ohio), in February 1862 for three years' service, being commissioned Colonel of the 4th Tennessee Volunteer Regiment, which he organized. He nominally commanded said unit, which was eventually mounted and redesignated 1st Tennessee Cavalry Regiment, in the Western theater of the American Civil War.
In March 1862 he left from Washington for Nashville, with his father, newly named as military governor of Tennessee, Johnson's secretary William A. Browning, and two Tennessee Congressmen, Horace Maynard, and Emerson Etheridge. In summer 1862, "Andrew Johnson exchanged communications with General George W. Morgan, begging him to watch over Robert and to encourage him to do his duty. The general responded with positive news." Years later, an Ohio newspaper writer wrote that circa October 1862, as the outnumbered federal army abandoned the Cumberland Gap and retreated to safer ground in Ohio, "between Portland and Gallipolis, the military authorities forbade every doggery keeper on the road letting [Robert Johnson] have any liquor, on account of his violent character when drunk."