The marker for Richardson’s Division of the Second Army Corps is on the north side of the Sunken Road. (Sunken Road East tour map)
Richardson's Division, Second Army Corps, marker 44 of the War Department Union markers at Antietam

From the marker:

U.S.A.

Richardson’s Division, Second Army Corps

Maj. Gen. Israel Richardson, Commanding.

September 17, 1862.

Richardson’s Division crossed the Antietam at Pry’s Ford about 9:30 A.M., and advanced to the ravine behind the high ground overlooking Roulette’s house, where it formed line of battle as follows: Meagher’s Brigade on the right, Caldwell’s on the left and Brooke’s in reserve. The Division advanced on French’s left and engaged the enemy near this point. After a stubborn and varying contest of two hours the enemy was forced back from the Bloody Lane, to and beyond the Hagerstown Pike. Near the close of the action Major General Richardson was mortally wounded.

He was succeeded in command by Brig. Gen. W.S. Hancock and the Division was withdrawn, from its advanced position, to the high ground north of this road where it remained through the day.

No. 44.

See the Order of Battle for Richardson’s Division of the Second Corps at Antietam.