Two centuries after the bloodiest battle of the American Revolution, archaeologists are digging up a concrete lot in Brooklyn, N.Y., to settle a mystery over the mass grave of famed Maryland soldiers.

Known as the “Maryland 400,” the soldiers’ stand on the battlefield in 1776 earned Maryland the distinction of the “Old Line State.” The young men from Baltimore, Annapolis and beyond died while stopping the British from quashing America’s rebellion just as it began.

The city of New York bought the vacant lot at Ninth Street and Third Avenue long presumed to conceal the Marylanders’ bones. The city plans to build a pre-kindergarden school there. Preservationists requested an archaeological investigation before any construction begins.

“They played a major role in saving the American Revolution,” said Bob Furman, an author and president of the Brooklyn Preservation Council. “They deserve better than what they have gotten.”

What they have gotten, Furman says, is an undignified resting place. He spent years gathering historical records — deeds, maps, newspaper articles and letters — that suggest the Marylanders’ remains may rest beneath the lot located next to an American Legion post in northwest Brooklyn.

Enclosed by a chain-link fence and tagged with graffiti, the vacant lot itself offers no sign of the bones presumed buried below. For years, the only hint of hallowed ground was a placard hanging next door: “Here lie buried 256 Maryland soldiers who fell in the Battle of Brooklyn.”

New York State officials acknowledged the site when they hung the placard in 1952. Half a century later, they installed a second sign that designates the lot “presumed” burial grounds.

Over the years, attempts to exhume the lot have been mostly blocked by its private owners. Historians have questioned whether a mass grave of the Marylanders actually exists. The theory remained largely untested until now.

New York’s State Historic Preservation Office requested the archaeological survey, and crews began digging last month.

An archaeological report is due after the dig. A New York schools spokesman couldn’t say when the report will come, but historians from Maryland to New York await the findings.

“There are some people who are very certain that there is a mass grave to find. I don’t know that there is . . . simply because they would have been killed in different locations,” said Owen Lourie, a historian with the Maryland State Archives. He runs the archives’ Maryland 400 research project.

Four hundred may not represent their actual numbers, Lourie said. Researchers believe that about 250 of the Marylanders were killed or captured. Soon after their heroic stand, the regiment’s legend spread.

Brooklyn was a swamp in 1776, and the Marylanders actually fell in battle about six blocks northeast of the vacant lot, said Kimberly Maier, executive director of the Old Stone House & Washington Park historic site dedicated to revolutionary Brooklyn.

“I hate to disappoint you — there is no mass grave,” she said. “The British and Dutch would have traditionally buried traitors where they fell.”

But it’s precisely the swampiness of the battlefield that causes some to speculate about the vacant lot. It was once a wooded island in the swamp and could have been the only dry ground suitable for burial.

An 1835 farm deed refers to a graveyard there, wrote William Parry, an anthropology professor at Hunter College in New York, in a 2013 study of the grounds.

Fearsome German mercenaries known as Hessians fought alongside the British. According to Parry, one British officer wrote, “Some of the Hessians told me they had buried between 400 and 500 in one pit.”

The lot has also remained mostly untouched in the redevelopment of Brooklyn.

“A thorough search needs to be made,” said Furman, of the Brooklyn Preservation Council.

In the summer of 1776, British warships sailed for New York in the largest fleet since the Spanish Armada. About 22,000 troops marched from the shores of Brooklyn.

Gen. George Washington amassed his Continental Army to defend the strategic New York harbor. Outnumbered 2-1, the Americans formed a semicircle with a regiment of about 950 Marylanders anchoring the right end. They were in their early 20s, these farmers, tradesmen and sons from wealthy Annapolis families. Others mustered from Western Maryland to the Eastern Shore. “Men with absolutely no combat experience,” Lourie said.

The fighting erupted before sunrise Aug. 27, 1776. British forces overwhelmed the left end of the American line, and the formation collapsed into panic and confusion. American commanders ordered a retreat. Amid the chaos and musket smoke, half the Maryland regiment remained, about 400 men.

The Marylanders drew together under their Baltimore-born commander, Maj. Mordecai Gist. Against suicidal odds, they charged again and again.

Their stand held the British at bay while Washington’s army escaped to fight again. Since that time, Maryland’s proud title of the “Old Line State” has been stamped on coins and painted on road signs.

“To be able to identify the final resting place of the Maryland heroes would be a tremendous find,” said retired Maj. Gen. James Adkins, former commander of the Maryland National Guard and first vice president of the Maryland Society Sons of the American Revolution.

Former governor Martin O’Malley visited the Brooklyn battlefield about four years ago and met with members of the American Legion next to the lot. Today, the members are watching the dig next door closely.

“Everybody’s all hopped up and excited and hoping they find the remains,” said Peter DeAngelis, an 85-year-old Korean War veteran.

The veterans have quietly served as stewards over the presumed burial ground for decades. Each year, they assemble with their rifles to read the names of the Marylanders, and someone rings a bell softly between each name.

Even if the dig reveals nothing, the veterans say they will continue their small salute each year to the men of the Maryland 400, wherever they may rest.

— The Baltimore Sun