https://www.history.com/this-day-in-history/americans-suffer-worst-defeat-of-revolution-at-charleston?cmpid=email-hist-tdih-2021-0 [login to see] 1&om_rid=
After a siege that began on April 2, 1780, Americans suffer their worst defeat of the revolution on May 12, 1780, with the unconditional surrender of Major General Benjamin Lincoln to British Lieutenant General Sir Henry Clinton and his army of 10,000 at Charleston, South Carolina.
With the victory, the British captured more than 3,000 Patriots and a great quantity of munitions and equipment, losing only 250 killed and wounded in the process. Confident of British control in the South, Lieutenant General Clinton sailed north to New York after the victory, having learned of an impending French expedition to the British-occupied northern state. He left General Charles Cornwallis in command of 8,300 British forces in the South
South Carolina was a deeply divided state, and the British presence let loose the full violence of a civil war upon the population. First, the British used Loyalists to pacify the Patriot population; the Patriots returned the violence in kind. The guerrilla warfare strategies employed by Patriots Francis Marion, Thomas Sumter and Nathanael Greene throughout the Carolina campaign of 1780-81 eventually chased the far more numerous British force into Virginia, where they eventually surrendered at Yorktown on October 19, 1781.
Having suffered the humiliation of surrendering to the British at Charleston, Major General Lincoln was able to turn the tables and accept Cornwallis’ ceremonial surrender to General George Washington at Yorktown on October 20.