The British plan to take Charleston was born from frustration. After their northern strategy collapsed at Saratoga in 1777 and France entered the war, British commanders shifted their focus south, where they believed large numbers of loyalists would rally to the Crown. In December 1779, the day after Christmas, Clinton sailed from New York with approximately 8,500 troops and 5,000 sailors aboard 90 transport ships escorted by 14 warships. It was one of the largest British amphibious operations of the war. By February 11, 1780, Clinton had landed his army on Simmons Island, about thirty miles south of Charleston. He then began a slow, methodical advance up the peninsula toward the city. Lincoln, commanding the garrison, debated whether to evacuate or stand and fight. Charleston's civilian leaders pressured him to stay, and he chose to defend the city. It was a decision that would prove disastrous.

Clinton's approach was patient and relentless. By late March, British forces had crossed the Ashley River and begun digging siege lines. On April 9, British warships forced their way past Fort Moultrie into Charleston Harbor. The garrison at the fort fired furiously but could not stop the fleet. With the harbor now under British control, Charleston's connection to the sea was severed. Clinton's total force, bolstered by reinforcements, swelled to nearly 13,000 troops against Lincoln's roughly 5,000 defenders. The British siege works crept closer to the city's defensive lines, and on April 13, Tarleton's raid at Monck's Corner eliminated the last American escape route. Lincoln attempted to negotiate terms on April 21, but Clinton rejected his proposals. The bombardment intensified, with the British employing heated shot that set buildings ablaze. For weeks, the city endured artillery fire while its defenders grew weaker.

On May 12, 1780, Lincoln surrendered. The scale of the disaster was staggering. Approximately 5,000 Continental soldiers and militia laid down their arms - the largest American surrender until the fall of Bataan in World War II. The British captured four American ships, a frigate, enormous quantities of weapons and ammunition, and the entire military leadership of the southern theater. American casualties during the siege totaled about 90 killed and 140 wounded, while the British lost roughly 76 killed and 182 wounded. But the real damage was strategic. The loss of an entire army left the southern colonies virtually undefended. British forces fanned out across South Carolina, establishing garrisons and attempting to pacify the countryside. Clinton sailed back to New York, leaving Cornwallis to complete the conquest of the South.

The fall of Charleston was supposed to end American resistance in the South. Instead, it ignited it. The harsh British occupation, combined with Tarleton's brutal tactics against surrendered troops at the Battle of Waxhaws later that month, turned neutral South Carolinians into partisans. Guerrilla leaders like Francis Marion, Thomas Sumter, and Andrew Pickens waged a relentless irregular war that made British control outside their garrison towns almost impossible. Within a year, the Continental Army sent Nathanael Greene south with a new force, and the grinding campaign that followed pushed the British back toward the coast. Charleston remained in British hands until December 14, 1782, when the last redcoats evacuated. The American Battlefield Trust and its partners have worked to acquire and preserve battlefield land in Charleston related to the siege. Today, the siege lines and fortifications are long gone beneath the modern city, but the ground where Lincoln surrendered an army remains one of the most consequential sites of the American Revolution.