Barbour was born on June 10, 1775, in Orange County, the second of four sons and second of eight children of Thomas Barbour and Mary Pendleton Thomas Barbour. His parents both came from prominent landed families, and his father served in the House of Burgesses before the American Revolution (1775–1783) and was a justice of the peace for fifty-seven consecutive years. Despite family financial reverses that prevented Barbour from attending college, for his time he still enjoyed considerable privileges. After preparatory study in rhetoric and classical languages at James Waddel’s local academy, Barbour read law in Richmond and in 1793, when he was still only eighteen years old, was admitted to the bar and began practicing law in Orange and the neighboring counties.
On October 20, 1795, Barbour married his cousin Lucy Maria Johnson, daughter of another prominent Orange County planter and later a prominent leader of Whig women. They had four sons and three daughters during the ensuing quarter century, the last of whom was B. Johnson Barbour, rector of the University of Virginia. Barbour prospered as a lawyer and in his management of large landholdings in Orange County. In 1817 he began to build an elegant plantation house from a design prepared by his friend Thomas Jefferson. For the rest of his life Barbour resided at Barboursville plantation in Orange County when politics permitted.
Politically ambitious, Barbour used his law practice and family connections, including close ties to James Madison, to win election to the House of Delegates in 1798. He played a leading role in obtaining passage of Madison’s Virginia Resolutions against the Alien and Sedition Acts with speeches extolling state sovereignty, strict construction of the Constitution, and limited government. He won reelection in 1799 and served until 1803, sat for another term in 1804, and returned to the House from 1807 through 1812. From December 1809 to January 1812 he served as Speaker of the House of Delegates.
Barbour ran for governor of Virginia in 1811 but on December 5 of that year the General Assembly narrowly elected acting governor George William Smith by a vote of 100 to 97. After Smith died on December 26 in the Richmond Theatre fire, on January 3, 1812, the General Assembly elected Barbour governor to succeed him. He was reelected twice and served from January 4, 1812, to December 11, 1814. Barbour’s three terms spanned the difficult years of the War of 1812, during which the state was beset by money problems and he struggled to keep militia in the field to protect Virginia from invading British fleets and armies.
Barbour’s experiences as governor wrought a major change in his political philosophy. The restrictive political dogma that he and other Republicans had fashioned when they were out of power during the 1790s no longer seemed adequate to him. The nation’s society and economy had become much more complex, and he came to value centralized banking and massed capital that could pay for roads and canals to facilitate the movement of people and goods and allow for the support of a strong military establishment to protect the nation from potential enemies. After three years as one of the best governors the Jeffersonians gave Virginia, Barbour was ineligible for reelection. A coalition of Republicans and Federalists in the General Assembly elected Barbour to the U.S. Senate on November 14, 1814, by a vote of 107 to 80 over the reluctant candidate of the traditional Republicans, William Wirt.
Along with many other national leaders who emerged from the War of 1812, by the time he entered the Senate Barbour was willing to vote for protective tariffs and other incentives to encourage manufacturing and commerce. He had a major hand in winning Senate approval of the bill to charter the Second Bank of the United States in 1815, and two years later he helped steer through the Senate John C. Calhoun’s Bonus Bill to appropriate funds for the construction of internal improvements to stimulate economic development and promote national defense. After President James Madison vetoed the bill on constitutional grounds, Barbour tried unsuccessfully to pass a constitutional amendment to grant Congress the contested power. He ably defended southern interests during the initial debates over the admission of Missouri as a slave state, but unlike his brother Philip Pendleton Barbour, a rising conservative member of the House of Representatives, he subordinated section to national considerations and helped enact the compromise that ended the political crisis. Barbour was an able parliamentarian, popular orator, and hard-working committee member. He often worked closely with Madison and with President James Monroe on both domestic and foreign policies. He became chairman of the Senate Committee on Foreign Relations in 1816, and in 1819 he was elected president pro tempore of the Senate.
In March 1825 President John Quincy Adams appointed Barbour secretary of war. Barbour succeeded John C. Calhoun in that office and for the most part continued Calhoun’s innovative policies. He accelerated construction of the National Road as a defense measure and pushed other internal improvement projects. As the government official responsible for Indian affairs, Barbour tried to protect the southern Indian tribes, especially the Creeks and Cherokees in Georgia, from encroaching settlers. Governor George Troup, of Georgia, defied Barbour’s policy in a challenge to the federal government that was popular among states’ rights leaders in Virginia and further alienated Barbour politically from many of his old allies.
In May 1828 Adams appointed Barbour minister plenipotentiary to Great Britain. On August 1 he sailed for England, but his career as a diplomat lasted only a year before Adams’s successor, Andrew Jackson, recalled and replace him in May 1829. Before he began his return voyage on October 1, 1829, Barbour received a doctor of civil law degree from Oxford University and visited the Marquis de Lafayette in France.
Barbour returned to Barboursville to manage the 5,000 acres of land he owned there and his labor force of more than 100 slaves. Barbour ran his plantation as a model farm. A student and vigorous advocate for scientific farming, he conducted many experiments to restore soil fertility, prevent erosion, and increase crop yields. He publicized the results during his presidency of the Albemarle Agricultural Society and with articles in national farm journals and newspapers such as the Farmer’s Register and the American Farmer. Barbour advocated establishing a state board of agriculture to promote scientific farming and a professorship in agriculture and an agricultural experiment station at the University of Virginia. He raised imported Merino sheep and some of the finest thoroughbred horses in Virginia. Although he had broken with many old Jeffersonians over issues of national politics, Barbour shared their devotion to agriculture as the foundation of a republican society and supported Jefferson’s proposed system of public education in Virginia.
In December 1830 Barbour returned to the House of Delegates as Orange County’s representative but resigned two months later in favor of his opponent, Thomas Davis, who had contested the election. He then served as chairman of the 1831 convention of the National Republican Party that nominated Henry Clay for president and helped organize the Whig Party in Virginia. Barbour also chaired the December 1839 Whig Party convention that nominated William Henry Harrison for president, and he worked for Harrison in the campaign. Barbour’s health began to fail in 1839, and he died of prostate cancer at home on June 7, 1842. He was buried in the family cemetery at Barboursville.