Clinton wanted to immediate cut the American line of communications via the Cooper River–but Arbuthnot refused to risk his ships beyond Sullivan’s Island until the army eliminated American gun batteries around Point Pleasant. Clinton instead sent Lt. Col. James Webster’s brigade of 1,200 troops to sweep the upper Cooper River valley. En route, Lt. Col. Banastre Tarleton’s British Legion dragoons intercepted an American message describing the American defenses around the strategically important Biggin Bridge at Monck’s Corner–Brig. Gen. Isaac Huger’s force of 500 solders, mostly Lt. Col. William Washington’s dragoons and several companies of poorly equipped militiamen. Tarleton’s troopers and infantry seized Biggin Bridge in a predawn raid on 14 May 1780 that netted 63 Americans, 185 horses, Huger’s supply train, and a copy of Lincoln’s defensive plan for Charleston. Tarleton’s New York Loyalist troops afterwards treated both Patriot prisoners and civilian sympathizers with brutality. Clinton disciplined the worst offenders, but word of the Loyalist excesses convinced many Carolinians to embrace the revolutionary cause. On 6 May 1780, Tarleton’s Legion crushed the remaining American dragoons at Lenud’s Ferry on the Santee River, which yielded 100 more fine Virginia horses and the Continental weapons and equipment.
"On the 12th of April, Lieutenant-colonel Tarleton...moved out in the evening...to surprise the Americans: An attack in the night was judged most advisable, as it would render the superiority of the enemy’s cavalry useless, and would, perhaps, present a favorable opportunity of getting possession of Biggin bridge...At some distance from the creek, a negro was secured...a letter was taken...It was evident, that the American cavalry had posted themselves in front of the Cooper river, and that the militia were placed in a meeting house, which commanded the bridge...on the opposite bank. At three o’clock in the morning, the advanced guard...[charged] the enemy grand guard on the main road...The Americans were completely surprised. Major Vernier of Pulaski’s legion, and some other officers...who attempted to defend themselves, were killed or wounded; General Huger, Colonels Washington and Jamieson...fled on foot to the swamps...where they effected their escapes. Four hundred horses...with their arms and appointments, (a valuable acquisition for the British cavalry in their present state) fell into the hands of the victors...Major [Charles] Cochrane was ordered to force the bridge and the meeting house with the infantry of the British legion: He charged with fixed bayonets...and dispersed everything that opposed him...This final instance of military advantage, may be partly attributed to the judgment and address with which the expedition was planned and executed, and partly to the injudicious conduct of [Huger]; who besides making a false disposition of his corps, by placing his cavalry in the front of the bridge...his infantry in the rear, neglected sending patrols in front of his [mounted sentinels]; which omission, equally enabled the British to make a surprise, and prevented the Americans recovering from the confusion attending an unexpected attack."
Lt. Col. Banastre TarletonBanastre Tarleton, “A History of the Campaigns of 1780 and 1781 in the Southern Provinces of North America.” London, 1787, pp. 17–18.