Buchanan was born near Dumfries, Scotland, in 1748. His father’s name may have been Archibald Buchanan, but his mother’s name is not known. His elder half brother James Buchanan moved to Virginia about 1757 and became one of the most influential and prosperous merchants in. John Buchanan briefly studied law in London, but the subject did not interest him, and about 1771 he joined his brother in Richmond. Commerce did not satisfy him either, and after fifteen months he returned to Scotland and may have received an AM from the University of Edinburgh in April 1774. On August 13, 1775, the bishop of London licensed Buchanan for the ministry of the in Virginia.
Buchanan lived in or near Richmond for about three years while serving at Deep Run Church in Henrico County as curate to Miles Selden, the rector of Henrico Parish. Buchanan supplemented his income with work as a tutor for‘s family. On October 1, 1779, he began preaching in Lexington Parish in Amherst County and became its rector in January 1780. On May 10, 1785, he succeeded Selden as rector of Henrico Parish and minister of Saint John’s Church in Richmond. He inherited much of the large and valuable estate of James Buchanan, who was one of the directors of the state’s public buildings in Richmond when he died on October 10, 1787, and he was probably the principal heir of his one known full brother, Alexander Buchanan, who died in Richmond about 1802. Buchanan’s inheritances enabled him to live an easy life and indulge his social nature. A jovial man with a subtle sense of humor who became one of the most popular people in Richmond, he hosted the Richmond Quoit Club at his farm just outside the city and contributed to many philanthropic causes. Buchanan also served for several years as president of the Amicable Society.
The College of William and Mary awarded Buchanan an honorary DD in 1794, and he was the founding president of the Bible Society of Virginia in 1813. For several years when Saint John’s Church was in disrepair he preached to his congregation in the Virginia State Capitol, alternating Sundays with the Presbyterian minister John D. Blair. Buchanan and Blair became close friends. A lifelong bachelor, Buchanan spent many hours in Blair’s household and with Blair’s children. Buchanan and Blair traded puns and doggerel verse in a lighthearted way, and they preached religious tolerance and set an ecumenical example that distinguished them from some of the Methodists and Baptists of the city.
After the loss of seventy-six lives in the Richmond Theatre fire of December 26, 1811, Buchanan and Blair led the campaign to construct Monumental Church on the site of the disaster. The two clergymen may have intended that they and their congregations share the church, but the more numerous Episcopalians appropriated the building for themselves. The division between the congregations did not disrupt the friendship between the ministers. Their legendary friendship and the example of religious tolerance they set was well known to their contemporaries and embellished many years later in George Wythe Munford‘s(1884). The winning personalities of the two principals and Munford’s nostalgic prose style made the book a popular interpretation of Richmond’s early history.
Buchanan served for thirty-seven years as rector of Henrico Parish and for twenty-nine years as treasurer of the Diocese of Virginia. He turned down the proffered post of bishop after the death of the incumbent James Madison, citing his own advanced age. Buchanan died in Richmond on December 19, 1822, about three weeks before his friend Blair, and was buried beneath the chancel of Saint John’s Church in Richmond.