 The nearness of the Harlem River made Slang Berg a militarily strategic location.During the American Revolutionary War, Hessian soldiers "mounted a battery" at the hill "to command the mouth of the Harlem River".Despite the 18th-century local prominence of the Gouverneur Morris family, the name "Mount Morris" for the rocky formation, one of two the Dutch called the Ronde Gerbergte is of 19th-century origin