|Elevation||836 ft (255 m)|
|Time zone||UTC-6 ( CST)|
|• Summer ( DST)||UTC-5 ( CDT)|
Triune is an unincorporated community in eastern Williamson County, Tennessee, approximately halfway between Franklin and Murfreesboro. The community is located along the Wilson Branch of the Harpeth River. The intersection of former local roads State Route 96 (Murfreesboro Road) and the concurrency of U.S. Routes 31A and 41A (Nolensville Road) is here. The community is located just north of these roads interchange with Interstate 840.
The earliest recorded non-Native American settlement in the Triune area was by William Jordan, a man from Virginia who built a log cabin in the area in 1796, soon after the American Revolutionary War.  In the early 1800s, the community grew; it was then called Hardeman's Crossroads (or Hardeman Cross Roads) for an early landowner. Other settlers arrived from Virginia and Kentucky, often bringing slaves with them.
By the 1820s the community included several substantial buildings, including stores, saloons, and leather shops. Several local cotton plantations were developed in this area that had their own mills and cotton gins. Planters had brought in large gangs of enslaved African Americans to work at these plantations.  With their profits, they established Hardeman Academy in 1828 as a private school for boys. By 1830, Hardeman's Crossroads also had a post office.  The community later was called Flemingsburg. 
The name Triune was derived from the name of the Triune Methodist Church, built in 1849 as the first church structure in the community.  Five schools for white children were built between 1820 and 1845. 
During the Civil War, Triune was the scene of several engagements. Several Confederate brigades under General Braxton Bragg were stationed in the area in 1862, and in December 1862 the area was the scene of military activity related to the Battle of Stones River. After Bragg's defeat there, Union Army forces occupied Triune and erected fortifications at the crossroads.   Between April and June 1863, several cavalry skirmishes took place in Triune, including one in June in which Confederate forces led by Nathan Bedford Forrest succeeded in penetrating Union lines.   The Methodist and Baptist churches, several homes, and the Porter Female Academy, a girls' school, were destroyed by fire as a result of military action in 1863. 
The community slowly rebuilt after the war. As of the 1880s, Triune had 57 white residents.  On May 2, 1892, blacks in the area were reported to have started an uprising and killed at least three whites in retaliation for the mob lynching two days after of Ephraim Grizzard in Nashville. He had been taken from jail before trial and an estimated 10,000 whites had gathered to see him hanged from a city bridge and shot 200 times. Nashville is 30 miles north and the county seat of neighboring Davidson County. 
Dr. Jonathan Bostick, a Mississippi planter, had been a trustee of Porter Female Academy and knew it was destroyed in the war. Before his death in 1868, he made a bequest in his will to establish a "suitable site and buildings" for a new "female academy" in Tennessee.    Because his descendants contested the will, there was a long delay in implementing the bequest. Litigation reached the U.S. Supreme Court, which upheld his bequest. Some 11 acres (4.5 ha) of land in Triune were purchased for the development of what was called the Bostick Female Academy. It was built in 1892 and began operation in 1893.    The Bostick Female Academy operated until about 1900 as a girls' boarding and day school for whites, enrolling as many as 75 girls.
After the state started to fund public education, parents no longer supported private schooling.   The Hardeman Academy, built in 1828 as a boys' school, was converted to a public school. After it was destroyed by fire in 1904,   the Bostick Female Academy building was used as the community public school. It served this role until the mid-20th century; since then it has been purchased and used as a private residence. 
- The Bostick Female Academy building is now used as a private residence;  it was listed on the National Register of Historic Places in 1982. 
- Triune Methodist Church, built in 1874 on the foundation of the church's first building, is another 19th-century landmark building in town. 
- Several homes built in the early 19th century were also still standing as of 1988. 
- A more recent local landmark is Castle Gwynn, built as a replica of a 12th-century Welsh border castle. It was built as private residence beginning in 1980. In the early 21st century, it serves as the location of the Tennessee Renaissance Festival, a Renaissance fair held annually in May. 
- Thomason Associates and Tennessee Historical Commission (February 1988). "Historic Resources of Williamson County (Partial Inventory of Historic and Architectural Properties), National Register of Historic Places Inventory Nomination". National Park Service.
- Robert S. Brandt (1995), Touring the Middle Tennessee Backroads, page 180. John F. Blair, Publisher. ISBN 0-89587-129-7, ISBN 978-0-89587-129-9.
- THE WAR IN TENNESSEE.; The Positions of the Opposing Forces. General Rosecrans Massing His Forces at Murfreesboro. CONSTANT SKIRMISHING AT THE OUTPOSTS. New York Times, March 29, 1863
- THE WAR IN TENNESSEE.; ANOTHER FIGHT AT TRIUNE THE REBELS REPULSED. National Soldiers to be Executed for Desertion., New York Times, June 14, 1863.
- Bostick Female Academy historical marker, Edge of the Wildwood website, August 23, 2010
- "The Mob Had Its Way. Ephraim Grizzard Taken from Jail at Nashville and Lynched". The Richmond Item. Richmond, Virginia. May 2, 1892. p. 2. Retrieved April 27, 2018 – via Newspapers.com. (Registration required (help)).
- U.S. Supreme Court, Peters v. Bowman, 98 U.S. 56, 25 L.Ed. 91. October term 1878.
- Brandt (1995) says the building was used as a public school until 1957, but the historical marker on the property gives a date of 1949.
- John E. Acuff (2009), "Williamson County", Tennessee Encyclopedia of History and Culture.
- Jessica Muzo, "The Story Behind Castle Gwynn is a Labor of Love", Tennessee Home and Farm, March 1, 2007