 It was drawing near Gettysburg on July 1, when the 12th and 15th regiments were detached to guard the corps trains.The two regiments accompanied the corps trains to Rock Creek Church, near the battlefield.After the battle, regiment participated in the pursuit of Lee's Army of Northern Virginia across the Catoctin mountains to Middletown, Maryland, then back over South Mountain, through Boonsboro, to Williamsport by July 14.