General Henry Clinton ended the siege at Charleston, South Carolina, by accepting the surrender of General Benjamin Lincoln on this date in 1780.
General Clinton had left New York with a force of approximately 10,000 British regulars and Hessians in the winter with the objective of seizing the port of Charlestown (as it was known until 1783) and encouraging Loyalist citizens of South Carolina to actively support the Crown. The siege itself began in early April, and the city was completely surrounded by late April. Lt Col Banister Tarleton reported of the defenses –
The garrison, under the orders of Gen. Lincoln, was composed of ten weak Continental and State regiments of militia drawn from the Carolinas and Virginia, and of the inhabitants of the town, amounting in the whole to near six thousand men, exclusive of the sailors. The body of regular troops destined for service, though assisted by the militia and by the inhabitants, was scarcely adequate to the defense of such extensive fortifications.
Over 5000 American troops surrendered to the Crown forces. This surrender represented the largest number of American troops to surrender to a foreign army until the surrender at Bataan over 150 years later.
A good reference for the battle can be found at My Revolutionary War website, which includes the map that helps put much of the account in perspective. Another interesting site with a wealth of primary sources online. It includes an order of battle for both the Continental and Crown sides. The Guards did not take part in this action as they were still located in the northern colonies and would not arrive in the southern colonies until October of 1780, five months in the future.
One outcome of the siege is that General Clinton returned to New York, leaving a portion of his command in the Southern Colonies under the leadership of Lord Cornwallis, his second-in-command during the siege. A second is that the campaign began the bitter partisan war in the souther colonies, with little mercy being shown on either side.
