The second of July dawned humid and warm. The soldiers of both armies understood it "would be a day of bloodshed and that with some of us our next sleep would be the cold sleep of death," but few could have imagined how much blood would be shed or the scale of the battle the day would bring.

The Confederates had failed to destroy the Army of the Potomac's First and Eleventh Corps and forced them into a strong defensive position on the heights south of town. The exhausted survivors of both corps found a rallying point on Cemetery Hill. From here they extended their line east to Culp's Hill and south along the northern end of Cemetery Ridge. Throughout the night of July 1 and into the morning of July 2 both armies gathered their scattered forces and prepared their battle lines for a renewal of the fighting.

Maj. Gen. George G. Meade, commanding the Army of the Potomac, decided to await Confederate movements and therefore arranged his battle line for a defensive struggle. Taking the shape of a giant fishhook, the Union line extended for over three miles. The "barb" and "curve" of the hook was located on Culp's Hill, held by the Twelfth Corps (Maj. Gen. Henry Slocum) along with remnants of the First and Eleventh Corps on Cemetery Hill. Maj. Gen. Winfield S. Hancock's Second Corps occupied the Union center along Cemetery Ridge. Assigned to hold the Union left flank was Maj. Gen. Daniel Sickles' Third Corps, which was supposed to occupy the lower portion of Cemetery Ridge and Little Round Top. Meade's only reserve, the Fifth Corps (Maj. Gen. George Sykes), was located behind the army's right rear.

The Army of Northern Virginia's front line stretched from Benner's Hill, east of town, through the streets of Gettysburg, to the Lutheran seminary west of town and then southward along Seminary Ridge. Eventually the line would stretch the length of Seminary Ridge and threaten to overlap the Union position on Little Round Top. Before the day ended the Confederates would bring nearly the entire length of the Union line under attack.

Finding the battle forced upon him and "in a measure unavoidable," Gen. Lee decided to follow up his partial success of July 1 and assault the Union line on July 2, despite its obvious strength. He hoped to attack as early in the day as possible. One reason for his success on July 1st came from the fact that he did not face the full strength of the Army of the Potomac and the Confederates had been able to concentrate their forces more rapidly. If Lee hoped to outnumber the Union defenders again he would have to act quickly.

Sensing the key to the Union line was Cemetery Hill, but wanting to avoid a costly direct assault upon it, Lee developed a strategy he hoped would dislodge the Army of the Potomac by turning its position. Lee's plan was to crush the Union left with an irresistible assault "en echelon," that is, an attack that would strike the extreme left of the Union left and then progress, with fresh units pushed into the fray, northward, roughly following the Emmitsburg Road, along the Union line. Simultaneously, a successful demonstration by Lt. Gen. Richard Ewell's Second Corps against the Union right, at Culp's Hill and Cemetery Hill, would constrain Meade from pulling troops out of line to reinforce his left or, perhaps, succeed in turning the Union right. Meade's army held a strong position but, with the Sixth Corps still on the march, was not yet at full strength.

The assault against the Union left was to be led by Lee's most experienced corps commander, Lt. Gen. James Longstreet. Although his First Corps was one division short — Maj. Gen. George Pickett's Virginians were on the march from Chambersburg — Longstreet still had 14,000 men and Lee was confident that his battle-hardened veterans could carry the day. An early morning reconnaissance reported that the Union line did not extend to the Round Tops but ended on the southern end of Cemetery Ridge. Based on this report the Union flank appeared vulnerable.

In order to maintain surprise during his approach march, Longstreet attempted to keep his attack force concealed from the Union signal station on Little Round Top. In doing so, he conducted a laborious and time consuming march by taking advantage of various ridges, ravines and wood lots behind the Confederate line. Once completed, Longstreet placed his men under cover of Warfield and Seminary Ridge, opposite the Union left. Finally, sometime after 3:00 p.m. the main Confederate assault was ready to jump off.

The Union line awaiting this assault was arrayed much differently that what Longstreet expected. Earlier that afternoon Sickles ordered one of the most controversial movements of the entire battle. Responsible for holding the Union left, Sickles disliked his assigned position. He felt the ground he was ordered to occupy was too low, was not suitable for artillery, offered limited fields of fire and was "hopelessly dominated by the ridge in front" along which the Emmitsburg Road was located. For these reasons, and also fearing an imminent Confederate assault, Sickles moved his corps forward, without orders, to the terrain he found more favorable.

His new position formed a rough V-shaped line. Each of his two divisions formed one of the wings, the left being held by Brig. Gen. David Birney's 1st Division. Birney's left was anchored in Devil's Den and then extended northwestwardly through the Wheatfield and to the high ground at the Peach Orchard. Brig. Gen. Andrew Humphrey's 2nd Division formed the right wing, from the Peach Orchard northward along the Emmitsburg Road. This advanced line, between 500 yards and 3/4 of a mile beyond Sickles' assigned position provided excellent observation, along with fields of fire for artillery. But this advanced position had many faults; the most important being it covered too broad a front. The general had overextended himself to the point of leaving key terrain, such as Little Round Top, undefended, and he had moved beyond the effective support of the 2nd Corps on his right. Against a smaller scale attack the 3rd Corps may have formed an effective blocking force, but unsupported and isolated on exposed, high ground they were about to face the full force of Longstreet's attacking divisions.

Around 3:30 p.m. Longstreet's batteries opened a concentrated fire on Sickles' new line, thus signaling the beginning of the second day of battle. Learning of Sickles' unauthorized movement shortly before Longstreet's guns opened fire, General Meade realized it was too late to withdraw the Third Corps back to the original line he had assigned it to occupy. He ordered Sickles to maintain his position and ordered the Fifth Corps, his only reserve, to his support.

At about 4:00 p.m. Longstreet ordered his attack to begin and the brigades of General John B. Hood's division, holding the extreme right, stepped off. Almost immediately Lee's plan of attacking along the general axis of the Emmitsburg Road began to fray. Seeking to turn the Union position anchored at Devil's Den, Hood's attack drifted south away from its intended axis of advance. His far right flank advanced up Big Round Top toward an undefended Little Round Top, while his center moved against Devils' Den. Meanwhile, Union leaders, most notably General Gouverneur K. Warren, Chief Engineer of the Army of the Potomac, were scrambling to get Union infantry to Little Round Top before the Confederates. Warren managed to get a Fifth Corps brigade to the hill minutes before Hood's advancing troops. The battle for Little Round Top was soon joined. In the valley below, heavy fighting raged around Devil's Den and upon the adjacent Houck's Ridge. As more of Hood's division entered the battle it spread northward to the Wheatfield. Once Hood was fully engaged Longstreet fed half of General Lafayette McLaws' division into the battle, which extended the fighting even farther north to the Peach Orchard. Then around 6 p.m. he sent in the rest of McLaws' division to attack the Peach Orchard position from the west.

Taking advantage of his interior lines, Meade sent massive reinforcements to bolster Sickles' hard pressed line. These units, from the Second, Fifth and Twelfth Corps, approached not only from the army's secure rear areas but also from Cemetery Hill and Culp's Hill on the Union right. But by 6:00 p.m. the Peach Orchard position collapsed under a furious assault by McLaws' division and Sickles forward line began to crumble. Humphrey's division doggedly held their line along the Emmitsburg Road but the brigades of Maj. Gen. Richard Anderson's division of A. P. Hill's Third Corps now joined the assault and quickly rendered Humphreys' position untenable. Taking fire from both front and flank the last of Sickles' line was forced to retire, suffering heavy casualties in the process. Wilcox, Lang and Wright's brigades of Anderson's division pressed forward driving the Federal troops in their front and threatening the now weakened Union line on Cemetery Ridge. But Meade kept shifting troops to the threatened sectors and they blunted the drive of Longstreet's Corps and Anderson's brigades, although Wright's brigade was not turned back until some elements of it briefly penetrated the Union line just south of the famous Copse of Trees. By 7 p.m. the crisis to the Union left had passed and the Army of the Potomac, although battered, had weathered the storm of Lee's main offensive effort.

Just as the action on the Union left and center began to wind down, the Confederates opened their assault on the Union right. Originally seen as a diversion to be made in conjunction with Longstreet's assault, the attack by Ewell's corps against Culp's Hill and Cemetery Hill was anything but a side-show to the men involved.

Early on the morning of July 2nd Col. Isaac Avery's brigade of North Carolinians and Brig. Gen. Harry Hays' Louisiana brigade, were moved into the protective folds of the rolling terrain near the Culp farm. Meanwhile, the artillery battalion of Maj. John Latimer occupied Benner's Hill, a point of high ground about a mile east of Gettysburg and nearly a mile from the strong Union artillery position on East Cemetery Hill. Maj. Gen. Edward Johnson's division was also held in readiness behind Benner's Hill. During the afternoon, in conjunction with the cannonade that preceded Longstreet's assault, Latimer's gunners engaged Union artillery on East Cemetery Hill and Culp's Hill. During the duel Latimer was mortally wounded and the Confederate artillerymen were forced to abandon their position. Ewell's "diversion" was a failure.

As dusk began to settle over the fields and as Longstreet's assault on the Union left lost momentum, Ewell decided to order his men forward. His plan called for Johnson's Division to strike Culp's Hill, followed by a two-pronged attack against Cemetery Hill; Early's Division was to move against the hill's eastern face while Rodes' Division assaulted the hill's western slopes. Accordingly, Johnson's men moved out, first crossing Rock Creek and then moving up the steep, wooded and rocky slopes of Culp's Hill. This hill had been defended by the entire Union Twelfth Corps, who upon their arrival that morning built formidable entrenchments. But earlier in the day, as the threat on the Union left increased, Meade, feeling that he needed every soldier he could find to bolster his line, pulled nearly the entire Twelfth Corps from Culp's Hill and directed them to reinforce the left-center of the Union line. Only Brig. Gen. George Greene's brigade of New Yorkers was left on the hill to defend the Union right flank.

Greene's New York regiments were initially positioned near the summit of the hill. When the rest of the 12th Corps departed Greene began to extend his line towards Spangler's Spring, occupying some of the works abandoned by the removal of their comrades. Because of the confusion caused by the darkness and the unfamiliar, rugged terrain, the Confederates were not able to mount a unified attack. Instead, individual regiments or even companies struggled forward over boulders and around trees until they struck the Union line. Fierce firefights erupted, illuminated only by the flash of muskets, until one side broke off the action and faded into the darkness. Brig. Gen. George Steuart's brigade was able to occupy some of the abandoned entrenchments but Greene, who received some reinforcements from the 1st and 11th Corps, could not be dislodged from the main hill. The Confederates gained undisputed access to the Baltimore Pike but with the darkness, heavy fighting and confusing terrain, chose to hold their position until daylight and then push forward. By 11:00 p.m. the action on the Union right had sputtered to a conclusion and by then the Twelfth Corps began returning to Culp's Hill intent on re-occupying their former positions, and closing the way to the Baltimore Pike.

At dusk, as Johnson's Division struck the Union lines on Culp's Hill, Hays' and Avery's brigades were ordered advance against East Cemetery Hill. As they moved forward the rolling ground protected, then exposed them to Union artillery fire. Avery's men, on the left of the attacking line, suffered heavily from a Union battery placed on Steven's Knoll, between Culp's Hill and Cemetery Hill. But both brigades pressed forward striking the line of Union infantry at the base of the hill. The Union line collapsed with some of the fleeing soldiers falling victim to their own artillery firing in support from the top of the hill. In the smoke and confusion of twilight the Confederates gained the crest of East Cemetery Hill and several Union cannon positioned there. The Confederates had good reason to expect that the day was won since Rodes' division was expected to be attacking the hill's western slopes at the same time. Without informing Ewell, however, Rodes had decided such an attack was too risky and cancelled his advance. The Confederates on East Cemetery Hill met, instead of the expected reinforcements, Union troops from Hancock's Second Corps, who counterattacked and drove them off the hill.

The fighting of July 2nd had ended. It had been a bloody affair resulting in more than 16,000 casualties. The Union Third Corps lost 4,211 of this number and the Second and Fifth Corps suffered heavy losses as well. But the Southerners also suffered high casualties and much of the ground they gained had to be abandoned because it was too exposed to Union artillery. By day's end the Confederates had captured Devil's Den, the Peach Orchard and a section of Union entrenchments on the lower slopes of Culp's Hill, but all of the key terrain remained in Union hands. The battle's final outcome remained undecided.