Mention “the Victor at Saratoga” and people may think that you are talking about a horse. Yet that so-called victor, Gen. Horatio Gates, the commander of the American forces at the Battle of Saratoga, played a crucial role in the triumph there over the British forces of Gen. John Burgoyne in October 1777.

Though other figures of the War of Independence are still widely revered and studied, Gates faded from the national memory. He died in New York in 1806 and was buried at Trinity Churchyard in Lower Manhattan. Precisely where is not known.

On Sunday afternoon, more than 150 people gathered at the cemetery just off Wall Street to celebrate the installation of a marker that will serve as his gravestone and to highlight his long-neglected role in American history.

“This is a great day in my point of view in the history of the city of New York,” James S. Kaplan said in an address to the gathering, made up mostly of members of the Daughters of the American Revolution....