When Maj. Gen. Oliver Otis Howard, commander of the Army of the Potomac's Eleventh Corps, reached Gettysburg on the morning of 1 July 1863, he saw the tactical potential of Cemetery Hill should the Union forces at Gettysburg have to go on the defensive. As soon as his troops arrived, he established his headquarters on the hill and prepared to defend it as a rallying point. From the late afternoon of 1 July, when the Union First and Eleventh corps retreated to the hill, until the end of the battle, Cemetery Hill was the keystone of the Union position south of Gettysburg.
But it was not enough to occupy Cemetery Hill alone. If the Union position on Cemetery Hill was not to be turned, Union forces must also hold Cemetery Ridge to its left rear and Culp's Hill to its right. Maj. Gen. Winfield S. Hancock, whom Maj. Gen. George G. Meade sent to Gettysburg to take command of the forces there, ordered this done almost at once. Thus it was that the Army of the Potomac established its famed hook-shaped line at Gettysburg.
Gen. Robert E. Lee, who tried to hold the initiative throughout the battle, attacked the Union left and center on the afternoon of 2 July and the Union center on 3 July (in Pickett's Charge). Lt. Gen. Richard S. Ewell's corps of the Army of Northern Virginia was to support these attacks by simultaneous assaults against the Union right on Culp's Hill and Cemetery Hill. Ewell's decision not to try to seize these hills on the late afternoon of 1 July, the measures taken by Ewell's corps to cooperate with the Confederate attacks on 2 and 3 July, and the Army of the Potomac's defense of Cemetery Hill and Culp's Hill are the subject of this monograph.
The battles on Cemetery Hill and Culp's Hill were part and parcel of the battle of Gettysburg as a whole and were conceived as integral parts of the assaults on the Union left and center. Yet, as it turned out, they were essentially separate from Lee's two major thrusts and the Federal effort to repulse them. A small portion of the Twelfth Corps became briefly and actively engaged in the repulse of Longstreet's attack on 2 July. Although Eleventh Corps batteries fired at Confederate batteries prior to Pickett's Charge and briefly fired at troops on the left of the Confederate assault column, these efforts were tangential to their defense of the two important hills. Therefore, I have confined this monograph to the operations and