The monument at Antietam to William McKinley is south of the Burnside Bridge parking area. (Burnside Bridge tour map; 39°26’57.3″N 77°43’58.6″W; map location) It was dedicated on October 13, 1903, two years after his assassination.
From the monument:
January 29, 1843 – September 14, 1901
Fourteen Years Member of Congress
Twice Governor of Ohio 1892-3 and 1894-5
Twice President of United States 1897 – 1900 – 1901
Sergeant McKinley Co. E. 23rd Ohio Vol. Infantry, while in charge of the Commissary Department, on the afternoon of the day of the battle of Antietam, September 17, 1862, personally and without orders served “hot coffee” and “warm food” to every man in the Regiment, on this spot and in doing so had to pass under fire.