At the Battle of Gettysburg, he commanded the 12. Corps under General Meade's command. However, his actions on the first day of the engagement left him open to criticism from his peers and, later, from historians. While marching his corps toward Gettysburg, Slocum stopped at a prearranged site roughly five miles southeast of town on the morning of July 1, despite claims from subordinate officers that there was clear evidence that a battle was being waged. Beginning at 1:00 p.
Slocum received several requests from Major General Oliver O. Howard to advance to Gettysburg to support the 11. Corps, which was heavily engaged. Slocum hesitated and did not proceed toward Gettysburg until late in the afternoon, although he would have been the senior general on the battlefield.
As a result, Slocum did not reach the town and take control of the forces there until nearly 6:00 p. Corps had suffered heavy losses. His dilatory behavior later earned Slocum the derogatory nickname, Slow Come. Slocum commanded the troops at Gettysburg until approximately midnight, when Meade arrived on the scene. After arriving at the battle, Slocum and his men performed admirably.On the afternoon of July 2, when Meade ordered Slocum to deploy all the 12. Corps to the Union right, Slocum convinced Meade to allow him to keep one brigade on Culp's Hill. The decision later proved to be advantageous, as Brigadier General George S.
Greene's brigade withstood several spirited Confederate assaults on the strategic elevation. Reflecting on the actions of his Corps in the battle, Slocum said.
My own corps during this conflict was moved from one point of the line to another, and all of those thus moved had the satisfaction of knowing that, where the battle was waged by the enemy with the greatest fury, there our troops were concentrated, ready and eager to meet them. After the Battle of Gettysburg, Slocum with his Corps would be transferred to the western campaigns where he would do great service with Sherman's army. He resigned from the army on September 28, 1865. This monument was dedicated in 1913 and is located south of Gettysburg on the west side of the Baltimore Pike. The headquarters was on Powers Hill, to the west of the marker.