The Maryland Regiment had joined the Continental Army barely two weeks before the Battle of Long Island. Unlike most of Washington's Army, the Maryland contingent had been well drilled at home and were so well equipped – they even had
bayonets, a rarity for the Army – that the Regiment was known at home as the Dandy Fifth, and to the rest of the Army as "macaronis", the then current word for dandies. The Marylanders were put under
Lord Stirling's brigade. When the British under
Cornwallis surprised the Americans by circling around their rear, Stirling ordered all forces, other than the Marylanders, who were outside the fortified position on Brooklyn Heights to retreat there leaving behind himself and 4 companies of the 1st Maryland. Stirling led these men (who would come to be known as "The Maryland 400") against Cornwallis' 2,000 British soldiers who were massed around the
Old Stone House, a thick-walled
fieldstone and brick fortification near today's Fifth Avenue and 3rd Street that had been built in 1699 to withstand
Indian raids. In fierce fighting, the Marylanders charged the British forces six times to give their comrades time to make their way to safety with the rest of Washington's army in the Heights. Twice they managed to drive the British from the house, but as more British reinforcements arrived and the Marylanders casualties mounted, they finally had to give up the assault and try to get to safety themselves. Only Major
Mordecai Gist and nine others managed to reach the American lines. Of the others, 256 lay dead in front of the
Old Stone House and more than 100 were wounded/and or captured. The bravery of the Maryland Regiment earned them the name "immortals". The dead were buried in a mass grave consisting of six trenches in a farm field. The gravesite is located on what is now Third Avenue between 7th and 8th Streets. Until the widening of Third Avenue in 1910, the site was marked by a tablet that read: "Burial place of ye 256 Maryland soldiers who fell in ye combat at ye Cortelyou House on ye 27th day of August 1776." The result of the brief battle was stunning for the Americans. More than a thousand men were killed, captured, or missing. Generals Stirling and Sullivan were in the enemy's hands. The battalion had lost more than 250 of their number. Most of the Marylanders' casualties occurred in the retreat and desperate covering action at the Cortelyou House. Ultimately, of the original Maryland 400 muster, 96 returned, with only 35 fit for duty. Historian, Thomas Field, writing in 1869, "The Battle of Long Island," called the stand of the Marylanders "an hour more precious to liberty than any other in history." Four companies of the 1st Maryland stood as the final anchor of the crumbled American front line, and their heroic action not only saved many of their fellows but afforded Washington critical respite to regroup and withdraw his battered troops to Manhattan and continue the struggle for independence. Over time, the farm became the site of a
Red Devil paint factory, and the burial grounds became part of a factory courtyard open to the sky because of a deed restriction relating to the grave. More time passed. The paint factory gave way to an auto repair shop and the courtyard was roofed over. Today the heroes whom Washington himself lamented lie under the floor of the building that had housed the auto repair shop. They lie in their unmarked grave miles from a
Stanford White monument to their sacrifice in the form of a marble shaft topped with a sphere that stands at the foot of Lookout Hill in
Prospect Park. It was erected in 1895 as a gift of the Maryland Society of the
Sons of the American Revolution. The Old Stone House survived the battle and in later years became the first clubhouse of the baseball team that came to be known as the
Brooklyn Dodgers. It was destroyed in the 1890s, and rebuilt in the 1930s.{{Cite book|last=Gallagher |first=John J. ==Battle of Cowpens==