Prior to the days fighting on July 2, 1863, General Robert E. Lee sent out scouts to clarify the exact location of the Union forces he knew to be concentrating on the ridge to his east. Hearing from Captain Samuel R. Johnston that the far left of the Union line terminated along Cemetery Ridge north of Little Round Top, General Lee determined to concentrate his attack on what must have appeared to be an opportunity similar to that offered at Chancellorsville just two months earlier. In May, General Stonewall Jackson had marched, mostly unseen, to the unprotected right of the Federal forces, a location from which he lead a devastating flank attack. On this day, he would rely upon Lieutenant General James Longstreet to achieve a similar success. General Longstreet had orders to march his Corps around the Union left unseen and attack up the Emmitsburg Road. If all went according to plan, the Union line would again be rolled up like a wet blanket.

Partway through this march, striving to remain free of prying Northern eyes, Confederate officers saw that to continue on their current course would expose them to view from the Union signal station on Little Round Top. In response, General Longstreet ordered his men to reverse direction and find another route. In later years, what came to be known as "Longstreet's Countermarch" would serve as kindling for one of the many controversies swirling about the Battle of Gettysburg. Those who sought to lay blame for their Gettysburg defeat at General Longstreet's feet pointed to what they saw as his slowness to initiate the expected assault, a slowness impacted by the circuitous route of this march.

In his memoirs, "From Manassas to Appomattox", Longstreet barely mentions the countermarch offering only "Under the conduct of the reconnoitering officer (Captain Johnston), our march seemed slow,—there were some halts and countermarches." However, in his official report written shortly after the battle, Longstreet offers justification for his delays including a desire to delay the initiation of movement until more of his men had reached the battlefield. "Fearing that my force was too weak to venture to make an attack, I delayed until General Law's brigade joined its division. As soon after his arrival as we could make our preparations, the movement was begun. Engineers, sent out by the commanding general and myself, guided us by a road which would have completely disclosed the move. Some delay ensued in seeking a more concealed route."

General Joseph Kershaw of General Lafayette McLaw's Division of Longstreet's Corps would also write of the delay beginning with their movement from their early morning camp. "The command was ordered to move at 4 o'clock on the morning of the 2d, but did not leave camp until about sunrise. We reached the hill overlooking Gettysburg, with only a slight detention from trains in the way, and moved to the right of the Third Corps, and were halted until about noon. We were then directed to move under cover of the hills toward the right, with a view to flanking the enemy in that direction, if cover could be found to conceal the movement. Arriving at the hill beyond the hotel, at the stone bridge on the Fairfield road, the column was halted while Generals Longstreet and McLaws reconnoitered the route. After some little delay, the major-general commanding returned, and directed a countermarch, and the command was marched to the left, beyond the point at which we had before halted, and thence, under cover of the woods, to the right of our line of battle."

In his official report, General Lee would mention only, "The preparations for attack were not completed until the afternoon of the 2d. The enemy held a high and commanding ridge, along which he had massed a large amount of artillery. General Ewell occupied the left of our line, General Hill the center, and General Longstreet the right. In front of General Longstreet the enemy held a position from which, if he could be driven, it was thought our artillery could be used to advantage in assailing the more elevated ground beyond, and thus enable us to reach the crest of the ridge. That officer was directed to endeavor to carry this position."

Regardless of the attributed blame for the delays, the countermarch contributed to a later start to the Confederate assault on day 2 of the battle. Fighting began after Union General Daniel Sickles had moved his men forward from their designated position along Cemetery Ridge. It began closer to the time that the large Union 6th Corps arrived on the field. It started with less remaining daylight with which to follow up on any successes. It started around 4pm July 2, 1863.