With the French now involved, the British stepped up their efforts in the southern colonies since they felt that most Southerners were Loyalists. A campaign began in late 1778, with the capture of Savannah, Georgia. Shortly thereafter, British troops drove toward Charleston, South Carolina, the principal Southern port. The British also brought naval and amphibious forces into play there, and they managed to bottle up American forces on the Charleston peninsula. On May 12 General Benjamin Lincoln surrendered the city and its 5,000 troops, the greatest American defeat of the war.
But the reversal in fortune only emboldened the American rebels. Soon, South Carolinians began roaming the countryside, attacking British supply lines. By July, American General Horatio Gates, who had assembled a replacement force of untrained militiamen, rushed to Camden, South Carolina, to confront British forces led by General Charles Cornwallis. But the untrained soldiers of Gates's army panicked and ran when confronted by the British regulars. Cornwallis's troops met the Americans several more times, but the most significant battle took place at Cowpens, South Carolina, in early 1781, where the Americans soundly defeated the British. After an exhausting, but unproductive chase through North Carolina, Cornwallis set his sights on Virginia.
Source: U.S. Department of State