[2] Loyal to the British Crown during the American Revolution, the Harpes became outlaws after the war and began robbing and killing settlers in the remote frontier west of the Appalachian Mountains.

As the Harpes' crimes gained notoriety, vigilante groups formed to avenge their victims, and they were eventually tracked down and executed around the turn of the century.

Historians have noted the difficulties of differentiating between facts and subsequent legends of the Harpes and their exploits,[4] as there are few reliably certain records of their lives from the time period.

When the Revolutionary War began, the Harpes' father(s) tried to join the Patriot American forces but were denied due to earlier associations with British loyalists.

[8]: 240 [11] Little is known of the Harpes' precise whereabouts at the outbreak of the American Revolution; according to an eyewitness account by Captain James Wood, of the Continental Army, they joined a Tory "rape gang" in North Carolina.

[12] These predatory, violently-loyalist criminals took advantage of the general wartime lawlessness by beating, raping, stealing from, torturing and murdering all who they did not take-kindly to, as well as burning and destroying property (especially the farms of Patriot colonists).

Frank Wood claimed to have seen the Harpe brothers serving "loosely" as Tory militia at the Battle of Kings Mountain, in October 1780, under British commander Major Patrick Ferguson.

[12] Later, the Harpes served under the command of Lieutenant Colonel Banastre Tarleton's British Legion at the Battles of Blackstocks (November 1780) and Cowpens (January 1781).

[12] Following the decisive British defeat by Patriot and French forces at Yorktown (1781), the Harpes left North Carolina, dispersing with their Native American allies, the renegade Chickamauga Cherokee, to Tennessee villages west of the Appalachian Mountains.

On August 19, 1782, the Harpes accompanied a British-backed Chickamauga Cherokee war party to Kentucky at the Battle of Blue Licks, where they helped to defeat an army of Patriot frontiersmen led by Daniel Boone.

They may have disguised their Tory past from their Patriot neighbors by changing their original name of "Harper", which was a common Loyalist surname in Revolutionary War-era North Carolina.

The Harpes later confessed to the killings of a confirmed thirty-nine people, but the estimated combined total, including unknown victims, may number more than fifty.

They were also accused of murdering a local man named Johnson, whose body was found in a river, covered in urine, with his chest cut-open and filled with stones.

Next, a man named John Langford, who was traveling from Virginia to Kentucky, turned-up dead; a local innkeeper pointed authorities toward the Harpes.

The criminal pair was pursued, captured, and jailed in the state prison at Danville, Kentucky, from which they managed to escape; when a posse was sent after them, the young son of a man who assisted the authorities was found dead and mutilated by the Harpes, in an act of retaliation.

The pair then made their way to Cave-In-Rock, a natural cave on the bluffs above the Illinois bank of the Ohio River—and a stronghold of the river pirate and criminal gang leader Samuel Mason.

With their wives and three children in tow, the Harpes found a refuge with a crime gang led by Samuel Mason, who preyed on slow-moving flatboats making their way along the Ohio River.

After the murderous pair were found to have a habit of taking travelers to the top of the bluff, stripping them naked, and pushing them off, Samuel Mason forced the Harpe brothers to leave.

In August 1799, a few miles northeast of Russellville, Kentucky, Big Harpe bashed his infant daughter's head against a tree because he was annoyed by her constant crying, his only crime for which he would, later, admit to feeling genuine remorse over.

[1] WILEY HARP alias ROBERTS is very meagre in his face, has short black hair but not quite so curly as his brother's; he looks older, though really younger, and has likewise a downcast countenance.

[1] The Harpe killings continued in July 1799 as the two fled west to avoid a new posse, organized by John Leiper, which included the avenging husband and father Moses Stegall.

[21] William Faulkner in his novel Requiem For A Nun i1954, in describing the Paleolithic evolution of the area served by the Natchez Trace prominently mentions the exploits of the Harper's and Mason, highlighting the butchery and savagery of the early history of Yoknapatawtha County In the 1941 film The Devil and Daniel Webster (or All That Money Can Buy), Big and Little Harpe are part of the "jury of the damned" that Daniel Webster must convince in order to free an innocent Jabez Stone.

[23] In 2015, the Investigation Discovery television channel series Evil Kin aired an episode about the Harpe brothers called "Something Wicked in the Woods".