Williams was born in Hanover County, Virginia and was the son of Daniel Williams and Ursula Clark Henderson. His siblings included James, Joseph, John, Daniel, Henry, Marya Goodman, and Mary Mitchell. He was orphaned the week after his 17th birthday. He moved into the home of his brother, John, in Granville County, North Carolina. John, being a lawyer, gave him a basic education before James set out on his own. He settled on the Little River in South Carolina. By 1773, Williams had started a farm and built a mill in Ninety-Six District on the South Carolina western frontier, and was an officer in the local militia. Tensions rose before the revolution, as many of his neighbors took Loyalist positions. Williams supported the American cause. He joined the local Committee of Safety, and was elected to the state's Provincial Congress in 1775 and again in 1776.
War of Independence
In 1776, the Ninety-Six District militia split into Loyalist and Patriot factions. Williams was made a lieutenant colonel of a regiment, but he had to recruit and train the new men. He succeeded in organizing a militia group, but pressure from Britain and her Indian allies meant that Williams always had to leave some troops behind for home defense. Williams led forces of local men into action at nearby Briar Creek and Stone Ferry, and as far afield as the expedition to the Second Battle of Savannah. On August 19, 1780 he led his detachment into the Battle of Musgrove Mill. The Patriots' success there, even in such a limited engagement and coming so soon after the disaster of Camden, earned him a promotion to colonel.
Williams led a 100-man detachment to meet up with other militia from the overmountain settlements which were gathering to engage Cornwallis' western force led by Major Patrick Ferguson. He joined with the other units at Cowpens on October 6. The next day these forces won a major victory at the Battle of Kings Mountain, where the out-numbered Americans overwhelmed an 1,100 man Loyalist force, while suffering only twenty-eight fatalities. Col. Williams was one of them.
Memorials
Williams' original hastily dug grave at the site of the battlefield was later moved. His body was re-interred on the lawn in front of the Cherokee County Administration building, on Limestone Street in Gaffney, South Carolina. It is marked by a large memorial. The South Carolina Provincial Congress had promoted Williams to the rank of brigadier general, but he died before the commission could be delivered. In 2005, the South Carolina General Assembly confirmed the rank originally bestowed upon him 225 years before. In the same act, Gen. Williams was further honored by renaming the Little River Bridge, "James Williams Memorial Bridge", marking the northeast corner of what had been his plantation.