The most accurate response regarding the effectiveness of the Southern Strategy in Charleston is: Charleston was seized by the British, and 5,000 men surrendered.
The British victory at the Siege of Charleston in 1780 was one of the significant successes for the British in the Southern Strategy during the American Revolutionary War. The surrender of American forces, including approximately 5,000 troops, was a major setback for the Continental Army and highlighted the challenges faced by American patriots in the Southern theater at that time.