First Division Twelfth Army Corps

The monument to the First Division of the Twelfth Army Corps southeast of Gettysburg on Culp's Hill.

The division was commanded at the Battle of Gettysburg by Brigadier General Alpheus Williams, a lawyer and militia officer from Detroit, Michigan.

At the start of the battle Twelfth Corps commander Henry Slocum was given command of the right wing of the army, and when he arrived at Gettysburg on the late evening of July 1st he was senior commander on the field. Alpheus Williams became temporary commander of the Twelfth Corps during this time, with Brigadier Thomas Ruger taking command of the First Division.

Monument map: South Culp's Hill

From the monument:

Army of the Potomac Twelfth Corps First Brigade Brig. General Alpheus S. Williams Brig. General Thos. H. Ruger

First Brigade_ Col. Archibald L. McDougall Second Brigade Brig. Gen. Henry H. Lockwood Third Brigade Brig. Gen. Thos. H. Ruger Col. Silas Colgrove_

_July 1. Approaching Rock Creek on the Baltimore Pike the Division moved on a cross road to occupy Wolf Hill but retired at sunset and took position east of Rock Creek for the night. The _First_ and Sixth Corps having been included in Gen. Slocum's command Gen. Williams assumed command of the Corps. Gen. Ruger of the First Division and Col. S. Colgrove of the Third Brigade._

_July 2. Brig. _Gen. Lockwood's Brigade_ joined the Corps early in the morning not having been assigned to a division was subject to the direct orders of the Corps Commander until assigned July 5th to First Division. The Division at 8 A. M. crossed Rock Creek and formed on the right of Second Division its left on Culp's Hill the right in McAllister's Woods. Breastworks were constructed along the line. Late in the day the Division moved to support Third Corps and Johnson's Confederate Division advanced and occupied the vacant works._

July 3. At daylight attacked the Confederate Infantry and was hotly engaged with charges and countercharges at different points until 10:30 A. M. when the Confederate forces retired.

_July 4. Early in the morning _Gen. Slocum_ with a detachment of infantry and a battery made a reconnaissance in front to Gettysburg without opposition._

Casualties Killed 6 Officers 90 Men Wounded 27 Officers 379 Men Captured or Missing 1 Officer 30 Men Total 533

Thomas H Ruger