The Bivouac of Magilton’s Brigade marker is on the north side of Mansfield Avenue next to the War Department marker # 16 for Magilton’s Brigade and the monument to the 3rd Pennsylvania Reserves. (Mansfield Avenue tour map; 39°29’19.7″N 77°44’45.8″W; map location)

Magilton’s Brigade was part of Meade’s Division of Pennsylvania Reserves, who opened the Battle of Antietam with an attack south along the Hagerstown Pike at dawn on September 17. This marker shows the location of the brigade just before the attack.

From the marker:

 U.S.A.

 On the night of September 16, 1862, three regiments of Magilton’s Brigade, Meade’s Division bivouacked in the North Woods a few feet south of this point in support Seymour’s skirmishers. One regiment was in second line in the open ground north of this road.

D.