Joseph Martin, Jr. (1740–1808) was a brigadier general in the Virginia militia during the American Revolutionary War, in which Martin's frontier diplomacy with the Cherokee people is credited with not only averting Indian attacks on the Scotch-Irish American and English American settlers who helped win the battles of Kings Mountain and Cowpens, but with also helping to keep the Indians' position neutral and from siding with the British troops during those crucial battles. Historians agree that the settlers' success at these two battles signaled the turning of the tide of the Revolutionary War—in favor of the Americans.

Martin was born in Caroline County, Virginia, and later lived at Albemarle County and then at Henry County, Virginia, at his plantation, Belmont, on Leatherwood Creek in Martinsville, not far from the plantation of his friend Governor Patrick Henry, Leatherwood Plantation.

General Martin held many positions during his public life. As a very young man he first tried his hand at farming, next he worked for three years as an overseer on the huge plantation of his local Virginia kin, next he was a longhunter, and an explorer on the frontier for friend Patrick Henry, then an early pioneer and builder of Martin's Station in the "wild west," a surveyor of the KY/NC and TN/VA borders, an Indian agent/Indian fighter for Patrick Henry, a member at peace treaties with the Indians, and along with Dr. Thomas Walker, Joseph Martin named the Cumberland region and the Cumberland River, he served as a member of the legislatures of Virginia, Georgia, and North Carolina, he was lifelong friends with Gen. Thomas Sumter, he was also friends and brothers-in-law with Col. Benjamin Cleveland (both married Graves sisters), he was unsuccessfully nominated by Patrick Henry to the position of the first governor of the Southwest Territory, was the holder of some 80,000 acres across the Southeastern U.S. at one point. The city of Martinsville, Virginia, was named in his honor during his lifetime.

The son of planter Capt. Joseph Martin Sr. and his wife Susannah Chiles, great-granddaughter of Colonel John Page, Joseph Martin Jr. was raised in a Virginia gentry family in Caroline and Albemarle Counties. His father, Joseph Martin Sr., was the son of wealthy British merchant William Martin in Bristol, England, who sent his son to Virginia as supercargo aboard his ship the Brice. Martin Sr. wrote to his English father that he planned to marry the daughter of a common Virginia colonist. Even though she was from the Chiles family and was a descendant of Virginia's Col. John Page, to Martin's wealthy father back in England all American colonists were inferior to the English. William Martin of Bristol was himself Lord Mayor of Bristol and owner of a ship building company, a glass manufacturing plant, importer and exporter with the new world; including tobacco. The father wrote back disinheriting young Joseph Martin Sr., who never returned to England.

Joseph Martin Sr. was "a perfect Englishman", recalled his grandson later, "large and athletic; bold, daring, self-willed and supercilious. And in him was depicted, as my father has told me, the most complete form of the aristocracy of the British government." Capt. Martin arrived in Albemarle County in 1745, one of the original patentees. Joseph Martin Sr. left some 300 acres of his landholdings to son Joseph Jr. at his death in 1762. Nearby neighbors Dr. Thomas Walker, Peter Jefferson, James Madison, and the Lewis and Clark clans and kin including Lewis, Carr, Waller, Dabney, Hammock, Hughes, etc.

But Joseph Martin Jr., the grandson of the English immigrant, was not cut out for a Virginia gentry planter's life. "Gambling was a favorite pastime." Martin's son, Revolutionary War officer Col. William Martin, in his accounts of his father's life in the, "Lyman Draper Manuscript Collection," writes that although his father gambled, he was not much of a drinker and let his son in on his secret; Martin sometimes pretended to over-drink so he might appear to be drunk in order that fellow gamblers would let down their guard. As a youth, Joseph Martin ran off from an apprenticeship during the French and Indian War of 1756, and joined the army at Fort Pitt, where he served alongside another Virginia youth, Thomas Sumter. Following his early army service, Martin lit out for the rigors of the frontier, where he dressed in buckskin and was an early real estate speculator, trapper and fur trader and Indian fighter. But this time on the frontier was after Martin had bought a large plot of land in Henry County with his earnings working for three years as an overseer for an uncle. Martin also gained 20,000 acres of land from Patrick Henry in a surveying contest at Powell Valley. Martin's youthful adventures on the frontier were grist for later stories... some of which were written by Martin's political foes and were slanted to paint a picture of him in an unkind light. One writer, a fan of Martin's political enemy, called him lazy and refused to describe him by his military ranking. General Joseph Martin may have been many things in his lifetime, but a quick study of his history and his accomplishments show that he was far from lazy. Eventually the soldiering, trapping and Indian fighting transformed the young Martin into a fearsome explorer.

Among Martin's earliest excursions on the frontier was one made on behalf of family friend Dr. Thomas Walker. Martin's son, Revolutionary War officer Col. William Martin, describes the naming of the area and the river in a letter to historian Lyman Draper, "A treaty with the Cherokees was held at Fort Chiswell, Virginia on New River, then a frontier. On the return of the chiefs home, Dr.[Thomas] Walker, a gentleman of distinction, and my father, [General] Joseph Martin, accompanied them. The Indians being guides, they passed through the place now called Cumberland Gap, where they discovered a fine spring. They still had a little rum remaining, and they drank to the health of the Duke of Cumberland. This gave rise to the name of Cumberland Mountain and Cumberland River."

In 1769, Martin journeyed to Powell's Valley to attempt a settlement, a full 100 miles (160 km) ahead of any previous settlement. Martin and his party – which included his brother Brice and Mordecai Horde – had hoped to secure the 21,000 acres (85 km²) granted to Dr. Walker and themselves. Martin's Creek in the region where Joseph Martin attempted his settlement is today named for him. (Martin's Station, as the settlement was known, became a well-known stopover for westward-bound settlers for many years.) The settlement ultimately failed, which some historians have blamed on the inability of the Loyal Company to defend its title to the tract.