For six weeks, the city held off enemy troops, fighting the longest siege of the war to preserve the freedom of a newly founded nation.
Now, thousands of people walk the site every day without even realizing it is a battlefield -- the largest in South Carolina -- or the role it played in the holiday the country celebrates today.
"I'm always amazed when I give tours that people don't realize there was a major battle here in 1780," said Carl Borick, assistant director of the Charleston Museum and author of "A Gallant Defense: The Siege of Charleston, 1780.
"The siege is important. It was the largest battle in South Carolina during the Revolutionary War."
Today almost nothing remains to remind folks of that struggle, save for a bit of tabby unearthed on Marion Square. Last week, a national park preservation organization issued a report on the state of battlefields in South Carolina, and in it there was no mention of the Siege of Charleston grounds.
That may be because its status is "paved." How things change in a couple of centuries.
More than 230 years ago, what is now John Street was a moat, a blocked tidal creek of the Cooper River that penetrated deep into the peninsula. Vanderhorst and Charlotte streets roughly mark the parapet on the city side of that moat, all of which protected a fort that straddled what is now King Street.
The siege took place between present-day East Bay and Smith streets, from Spring Street south to Calhoun Street.
In a city obsessed with its Civil War history, its Revolution-era past often is forgotten. Until a historical marker recognizing the siege was put up on Marion Square this year, there was no reminder of the battle.
"It is something that is very often overlooked," said Mark Moloy, a former National Park Service intern here who was instrumental in getting the marker erected. "I just don't see a reason we can't honor the people who first founded South Carolina and the United States."
Some cynics might say the battle has been pushed out of the city's consciousness because it was a stinging defeat, perhaps the largest of the war. After years of trying to take the city in 1776 and again in 1779, the British set up on Hampstead Hill -- basically the corner of present-day East Bay and Columbus streets -- in April 1780.
Following six weeks of the siege, the Americans surrendered and the British took more than 5,000 prisoners, including three signers of the Declaration of Independence. Borick said the siege, and subsequent defeat of the colonists, actually set up a chain reaction that turned the course of the war in America's favor.
Charleston fell, in part, because many militia men -- worried by a rumor of smallpox in Charles Town -- did not show up to fight. That left them available for other South Carolina battles, at King's Mountain and then Cowpens, that set the course for American victory in the Revolution.
And the British victory at Charles Town left the Redcoats over-confident, thinking they had, in effect, conquered the Carolinas.
For all those reasons, Borick said, Charleston played an important role in America's Independence.
Don Barger, southeast regional director for the National Parks Conservation Association, last week released a report on the condition of the battlefields at King's Mountain, Cowpens and Ninety-Six. The idea, he said, is to highlight what remains to tell the story of these parks.
The loss of battlefields, in part, plays a role in how much of the South's role in the Revolution has been forgotten.
"When most people think of the Revolutionary War, they think it happened between New York and Virginia," Barger said.
Historians are happy to see a little more focus on the city's Revolutionary history these days.
Aside from the annual Carolina Day celebration, which marks the 1776 battle in which Col. William Moultrie repelled the British navy and army from Sullivan's Island, this year the Historic Charleston Foundation will highlight the lesser-known parts of that battle, namely the battle at Breach Inlet.
That day, about 780 patriots repelled more than 10,000 British troops trying to cross from Long Island (now the Isle of Palms) to take Sullivan's Island and its fort. On Wednesday, the Historic Charleston Foundation will offer free public presentations about that fight at its headquarters at 40 East Bay St.
"I'm hoping we'll be able to get more people interested," Moloy said. "That's what the (Siege of Charleston) marker is about. There is a ton of history but there's nothing much to see. Getting information out about it is an ongoing process."