The Battle of Blackstock's Farm, a military engagement of the American Revolutionary War, took place in what today is Union County, South Carolina, a few miles from Cross Anchor, on November 20, 1780. The battle marked the first time during the war that an American militia had defeated British regulars. After the defeat of Major Patrick Ferguson and the destruction or capture of his entire military force of 900 men at the Battle of Kings Mountain the previous month, the sparsely settled Carolina Backcountry had come increasingly under the control of the Patriots. Lieutenant General Charles Cornwallis, British commander in the Southern theater, ordered his most gifted subordinate Lieutenant Colonel Banastre Tarleton to abandon his chase of the guerrilla commander Brigadier General Francis Marion and instead disrupt the activities of Patriot militia Brigadier General Thomas Sumter, thereby returning confidence to Backcountry Tories. Meanwhile, Sumter had been gathering partisan volunteers and now had a thousand men under his command. On November 18, Tarleton's British Legion dragoons and the mounted infantry of the 63d Regiment were bathing and watering their horses on the Broad River when some of Sumter's raiders fired at them from the opposite bank. The British brought up a 3-pounder "grasshopper" field gun and easily scattered the partisans. But Tarleton "did not submit easily to insults."

Sumter placed Colonel Henry Hampton and his South Carolina riflemen in the farm outbuildings. Some units he stationed behind stout fences and others he screened in the surrounding woods. Tarleton came up late in the fall afternoon and chose to make a frontal attack against a numerically superior force, not waiting for his infantry and artillery to catch up. Realizing that the battle was going against him, Tarleton desperately ordered an uphill cavalry charge against riflemen firing from cover. As Henry Lumpkin has written, "caution never was Tarleton's outstanding virtue." So many dragoons were knocked from their horses that "the road to the ford was blocked by the bodies of men and fallen chargers, the wounded, still targets, struggling back over their stricken comrades and kicking, screaming horses." Still, the British forces fell back in good order. Tarleton and his force returned to the British base located at Brierly's Ford. Though Tarleton had succeeded in dispersing Sumter’s force, thus claiming a victory, the recklessness of his advance and relatively heavy losses did not go unnoticed or un-criticized, while, at the same time, Sumter, by February, had sufficiently recovered from his wound, and was back again in the field with his men, though not at that later time with all his old comrades.