of Maj. Gen. John Pope's Army of Virginia. On August 9, Banks's Corps fought at the Battle of Cedar Mountain as part of Pope's Northern Virginia Campaign, where the corps was again up against Jackson, and was again defeated, the 2nd Massachusetts suffering 173 casualties. However, the II Corps did not reach the Second Battle of Bull Run until after the battle was over. On September 17, the II Corps was redesignated as the XII Corps, Army of the Potomac, with the 2nd Massachusetts remaining in the 3rd Brigade of the 1st Division. During the Battle of Antietam, the XII Corps, commanded by Maj. Gen. Joseph K. Mansfield supported General Joseph Hooker's advanced through the cornfield during the morning phase of the battle and received heavy casualties including Lieutenant Colonel Dwight, who was mortally wounded. The regiment lost 12 killed and 51 wounded, among the wounded were Captains Francis and Robert Gould Shaw along with Lieutenants Crowninshield and Mills. General Mansfield was also killed in the battle and command of the XII Corps passed to General Henry W. Slocum. Later in the year, they marched to Fredericksburg, Virginia, but did not participate in the Battle of Fredericksburg. During this time, at Stafford Court House, Captain Shaw left the regiment to become colonel of the 54th Massachusetts Infantry. In May, 1863, the regiment participated in the Battle of Chancellorsville. In the battle, Stonewall Jackson's corps executed a surprise flanking movement and smashed into the right flank of the Army of the Potomac, severely damaging the unsuspecting XI Corps. The neighboring troops, including the XII Corps with the 2nd Massachusetts, entrenched hastily and was able to stop the Confederate advance before it overran the entire army. Battle of Gettysburg After Chancellorsville, the regiment marched north to Pennsylvania following General Robert E. Lee's Army of Northern Virginia. It participated in the Battle of Gettysburg. On July 3, the third day of the battle, it made an attack against the Confederate troops at the base of Culp's Hill, near Spangler Spring. The regiment's commander, 23-year-old Lieutenant Colonel Charles R. Mudge, replied to the order to attack, "Well it is murder, but it's the order." In the charge a bullet struck Mudge just below the throat and killed him instantly. The regiment suffered 137 casualties in the assault. After the battle, the regiment was sent to New York City to help end the Draft Riots