The monument at Antietam to the 5th, 7th and 66th Ohio Volunteer Infantry Regiments is across from the Dunker Chuch. (Visitor Center-Dunker Church tour map) It was dedicated in 1903.
From the monument
OHIO
5th Infantry
Commanded by Major John Collins
7th Infantry
Commanded by Col. Eugene Powell
66th Infantry
Commanded by Lieut. Major Orrin J. Crane
Tyndale’s (1st) Brigade
Greene’s (2d) Division
Twelfth Army Corps Army of the Potomac
5th 66th 7th
These three regiments became engaged about 7:30 A.M., September 17, 1862, advanced and drove the enemy from the woods near the Dunkard Church and were in action until 1:30 P.M. Their combined loss was 17 men killed, 4 officers and 87 men wounded, 2 men missing, total 110.
The 5th Ohio, 7th Ohio and 66th Ohio are also honored by monuments at Gettysburg.
Location of the monument
The monument to the 5th, 7th and 66th Ohio Infantry Regiments is north of Sharpsburg. It is on the east side of the Old Hagerstown Pike across from the Dunker Church. (39°28’31.4″N 77°44’47.0″W)
See more on the history of the 5th Ohio Infantry Regiment, 7th Ohio Infantry Regiment or 66th Ohio Infantry Regiment in the Civil War