By June 17, the Ninety Six garrison was low on food and ammunition. Cruger had expected a relief expedition from Charleston, but hope was turning into despair.
Suddenly, a farmer, casually riding near the American lines, spurred his gorse and dashed into the fort through heavy Patriot fire. He brought word to the beleaguered garrison that Lord Rawdon, with 2000 reinforcements was only two or three days away. Greene learned of Rawdon's approach from his scouts the same day.
Greene reluctantly ordered a final assault against the Star Fort and the Stockade Fort, signaling by cannon fire at noon on June 18. fifty men rushed into the ditch to pull down the sandbags on the fort parapets and open the way for the main body of American troops. A volunteer assault party from the fort circled from behind and charged the Americans with fixed bayonets. About fifty patriots were killed of wounded and the attack was broken.
After three-quarters of an hour, "seeing little Prospect of succeeding without heavy Loss," Greene ended the attack and ordered his army to retreat toward Charlotte.
The British had held Ninety Six against the American siege, but they could not keep it. Lord Rawdon arrived in June 21 and ordered Cruger to abandon the post and withdraw to Charleston. By early July, the trenches were filled, the town burned, and stockade walls demolished, and Ninety Six was abandoned.