There is a monument to them in Prospect Park, Brooklyn.
“The monument to the Maryland Four Hundred in Prospect Park, Brooklyn, New York, commemorates the contribution and sacrifice of the Maryland Line in the Battle of Long Island of the American Revolution. On August 27, 1776, some four hundred Maryland troops led a rear-guard action to check the British advance and allow the retreat of Washington’s greatly outnumbered army. The Marylanders launched six counter attacks at the Cortelyou house; on the last attack Cornwallis’ troops were reinforced and the Marylanders were swept to the Gowanus canal, where 256 were buried on a knoll within the mill ponds. The mass grave, now the southwest corner of Third Avenue between Seventh and Eighth streets, is a few blocks from the park. The marble, granite and bronze monument, designed by Stanford White, was repaired and treated by the Monuments Commission and rededicated on August 27, 1991.”
http://www.mdva.state.md.us/MMMC/md400Monument.html