Army of the Potomac

Under Major General George G. Meade, the Army of the Potomac consisted of eight army corps: the First Corps under Major General John F. Reynolds, Major General Abner Doubleday, and Major General John Newton; the Second Corps under Major General Winfield S. Hancock and Brigadier General John Gibbon; the Third Corps under Major General Daniel E. Sickles and Major General David B. Birney; the Fifth Corps under Major General George Sykes; the Sixth Corps under Major General John Sedgwick; the Eleventh Corps under Major General Oliver O. Howard; the Twelfth Corps under Major General Henry W. Slocum and Brigadier General Alpheus S. Williams; the Cavalry Corps under Major General Alfred Pleasanton; and the Artillery Reserve under Brigadier General Robert O. Tyler. On July 1, the First and Eleventh Corps arrived, fought north and west of Gettysburg, and fell back to Cemetery Hill behind the town, while the Twelfth Corps and a large part of the Third Corps arrived at the close of the day. On July 2, the rest of the Third Corps and the Fifth and Second Corps arrived in the morning, and the Sixth Corps in the afternoon. After the Third Corps advanced, it was attacked by Longstreet's Confederate Corps and Anderson's Division of Hill's Corps; the Fifth Corps and the First Division of the Second Corps went to its support, and fighting continued until nightfall, when the Union forces had been driven from their advanced position and the Confederates had been repulsed. On July 3, after the Twelfth Corps had vacated a large part of its line on Culp's Hill on the night of July 2 and Johnson's Division of Ewell's Corps had occupied the works, the Twelfth Corps attacked in the morning and regained the lines it had previously vacated. In the afternoon, Hill's Corps and Pickett's Division of Longstreet's Corps attacked the line of the Second Corps and were repulsed with great loss, and Stuart's Confederate cavalry attacked the Second Cavalry Division and the Second Brigade, Third Cavalry Division, and was repulsed.

Gettysburg, Pennsylvania · United States