A space opened up in the Union line: the commander of the 71st Pennsylvania ordered his men to retreat when the Confederates came too close to the Angle; south of the copse of trees, the men of the 59th New York (Hall's brigade) inexplicably bolted for the rear.
But a combination of inept artillery leadership and defective equipment doomed the barrage from the beginning. Longstreet's corps artillery chief, Col. Edward Porter Alexander, had effective command of the field; Lee's artillery chief, Maj. Gen. William N. Pendleton, played little role other than to obstruct the effective placement of artillery from the other two corps. Despite Alexander's efforts, then, there was insufficient concentration of Confederate fire on the objective.
The July 3 bombardment was mostly the largest of the war, with hundreds of cannons from both sides firing along the lines for one to two hours, starting around 1 p.m. Confederate guns numbered between 150 and 170 and fired from a line over two miles (3 km) long, starting in the south at the Peach Orchard and running roughly parallel to the Emmitsburg Road.
Confederate Brig. Gen. Evander M. Law wrote, "The cannonade in the center ... presented one of the most magnificent battle-scenes witnessed during the war. Looking up the valley towards Gettysburg, the hills on either side were capped with crowns of flame and smoke, as 300 guns, about equally divided between the two ridges, rain their iron hail upon each other.