NOTHING is visible at the intersection of Third Avenue and Eighth Street in the Gowanus section of Brooklyn to indicate that anything extraordinary is there. The artisanal-pie place on one corner and the auto body shops across the way suggest it is merely another spot in the city where grit is giving way to gentrification. But if a small group of history enthusiasts are right, this particular corner of Kings County is hallowed ground.

They believe that there is a mass grave a few dozen yards to the east of the intersection that contains the remains of American heroes: soldiers from the First Maryland Regiment under Col. William Smallwood, which saved Washington’s army during the Battle of Brooklyn on Aug. 27, 1776. Their burial site, these advocates say, deserves the same level of veneration accorded the military cemeteries at Gettysburg and Normandy.

The leader of the find-the-Marylanders group is Bob Furman, a Brooklyn historian and president of the Brooklyn Preservation Council, a nonprofit organization dedicated to maintaining brownstone Brooklyn’s look and feel. “The evidence is quite strong,” Mr. Furman said. “I’m confident enough that I tell everyone I know.”

But Mr. Furman has no way to test his theory. Right now, the site he is targeting is a vacant, concrete-covered lot studded with weeds and surrounded by a chain-link fence. The owners, who say they are interested in developing the property themselves or selling it to someone who will, have rebuffed his inquiries about conducting an archaeological probe on the site.