The marker for Ferrero’s Brigade of Sturgis’ Division is at the east end of Burnside’s Bridge. (Burnside’s Bridge tour map) The brigade’s story is continued on a marker on Branch Avenue.

Ferrero's Brigade, Sturgis' Division, marker 68 of the War Department Union markers at Antietam

From the marker:

U.S.A.
Ninth Army Corps

Ferrero’s Brigade, Sturgis’ Division

Brigadier General Edward Ferrero, Commanding.

Organization.
51st New York Infantry
51st Pennsylvania Infantry
21st and 35th Massachusetts Infantry

September 17, 1862

On the morning of the 17th Ferrero’s Brigade was in position about a half mile northeast of this point on the Rohrback Farm. About 9 A.M. it moved to the left and, after several changes of position, was ordered to carry the bridge. The 51st Pennsylvania and the 51st New York were formed under cover of the hill overlooking this point; skirmishers were thrown forward to the stone fence above the bridge and behind fences and trees along the stream below it; and, under cover of the fire from the Federal Artillery, the two Regiments charged down the hill, carried the bridge and formed, under cover of the bluff, in the road beyond it. The 35th Massachusetts, closely supported by the 21st Massachusetts, followed and ascended the bluff on the right where, later in the day, it was joined by the remainder of the Brigade and led the advance to the Otto farm lane, where it became severely engaged and lost heavily in killed and wounded.

Late at night the Brigade was relieved by Welsh’s Brigade of Willcox’s Division and fell back to the banks of the Antietam.

No. 68