It was 5 a.m. when A.P. Hill ordered Heth's division forward from Cashtown. Heth's division comprised roughly 7,500 men, quite a strong force for reconnaissance and so-called foraging. Nonetheless, it was a formidable force for Buford to face given that he had 2,400 effectives to meet the attack. However, Buford's cavalry was armed with breech-loading carbines, enabling a much more rapid fire relative to their counterparts' muzzle-loaders. This, Buford knew, would help keep things a little more even until Reynolds' I Corps could arrive from Emmitsburg.

The first shots were fired around 5:30 a.m., consisting mainly of skirmishing between the advanced pickets of both sides; the first shot fired by Union Lt. Jones of the 8th Illinois, three miles west of Gettysburg on the Chambersburg Pike (Hassler, 1970). The Confederate presence, if it could not be determined by the sound of gunfire, was reported to Buford immediately. Gamble's pickets were quite effective in slowing Heth's lead brigade under Brigadier General James Archer. And around 8:00 a.m. General Ewell's II Corps advance pickets were encountered by those of Devin. This alerted Buford to a dangerous Confederate presence to both his north and west, a prospect he fully expected.

Once Heth reached Herr Ridge, about a thousand yards west of McPherson's Ridge, he spotted what he could decipher as the main line of Union cavalry. He subsequently ordered the brigades of Archer (on the right) and Brigadier General Joseph Davis (on the left) forward to attack the Yankee position. It was about 8:00 a.m. when a desperate struggle between the two sides ensued along the banks of Willoughby Run. Both Confederate generals and their men were taken by total surprise by the tenacity and rapid fire of the Union troopers. While slowly falling back from the creek to the crest of McPherson's Ridge, the cavalrymen kept up a strong, incessant fire, keeping both Archer and Davis in check for nearly two hours despite being heavily outnumbered. In response to the rapid fire weapons the first Confederate prisoners respectfully shouted, "What you all do - load on Sundays and fire all week?" (Hassler, 1970, p. 32).

Map of early morning engagement

By 9:00 a.m. Heth's artillery was lobbing shells against Buford's line from Herr Ridge. McPherson's Grove, a small patch of woods where Heth was sure many of Gamble's men were gathered, was a particularly heavy target. Union artillery answered in kind from McPherson's Ridge, and an artillery duel accompanied the struggle between infantry and cavalry. By 10:00, Gamble's men were beginning to give way to Archer's onslaught and Devin's troops were facing the prospect of having to deal with two large Confederate divisions - Rodes and Early - coming from the north. The two were arriving almost simultaneously and Devin knew he would not be able to hold them. The Union line was in trouble.

Before Reynolds and the I Corps arrived to relieve Buford's weary troops, the cavalry commander sent this dispatch off to General Meade:

The enemy's forces are advancing on me at this point, and driving my pickets and skirmishers very rapidly. There is also a large force at Heidlersburg that is driving my pickets at that point from that direction. General Reynolds is advancing; and is within three miles of this point with his leading division. I am positive that the whole of A.P. Hill's force is advancing (Hassler, 1970, p. 34).

Hill's force was advancing, though not en masse. It was still only Heth's lead brigade. But those 7,500 men were enough to push Buford's troops to the limit.

It was shortly after 10:00 when Reynolds found Buford on the field. He urged Buford to hold on for as long as possible, for Wadsworth's 3,500 strong First Division of the I Corps was still some distance away. Riding back down the Emmitsburg Road to urge the men forward, Reynolds ordered all fences be torn down as to expedite the infantry's advance through the fields toward the fighting. He also sent for Major General Oliver O. Howard to push his XI Corps to Gettysburg. Finally, he sent word to Meade informing him of the new situation, saying he would fight behind barricades until help arrived (Coddington, 1968).

Just as Buford's men were about to give way, the first troops from the I Corps had arrived, Lysander Cutler's Second Brigade being the first. Two regiments were placed near McPherson's barn to protect the left flank of James A. Hall's battery located between the Chambersburg Pike and the railroad cut. Three more regiments were placed across the cut to protect Hall's right. Cutler's brigade of 2,000 would soon be engaged head-on with Davis' inexperienced but determined force consisting of roughly 2,300.

On the right in McPherson's Grove arrived the famed "Iron" Brigade under Solomon Meredith. Seeing the threat of Archer's men seizing the key wooded position, Reynolds himself urged two regiments in to push the Confederates back. While riding with them into the woods, Reynolds shouted, "Forward! men, forward! for God's sake, and drive those fellows out of the woods!" (Hassler, 1970, p. 40). Turning around to observe the other regiments coming up, the Union Left-Wing commander was killed by a stray minie-ball that entered the back of the head and exited under the eye. At approximately 10:15 a.m. the 43-year-old famed Union general was killed instantly. Major General Abner Doubleday would assume command of the entire I Corps, with Brigadier General Thomas Rowley succeeding Doubleday in command of his division (Coddington, 1968).

(It is important here to note that Reynolds, upon surveying the ground, took note of the importance of the eminence immediately south of town known as Cemetery Hill. His strategy was to continue to hold Buford's line of battle for as long as possible and then retreat to Cemetery Hill for another defense. Doubleday was also well aware of the strategic importance of the hill and did very well to live up to Reynolds' strategy by holding the positions west of town until late afternoon. However, it would be the arrival of Howard, who would assume full command because he outranked Doubleday, on East Cemetery Hill that would dictate Union success; he independently realized the hill's significance and placed an entire brigade on the heights for the purpose of reforming later in the day. Thus, all three generals were fully aware that they could not hold the present line all day and the army needed a centralized position on which to reform. It was this strategy that would ultimately lead to the Union army's success at Gettysburg. For if these generals believed for a moment that they could hold their present ground and therefore had not planned for retreat, it can be easily surmised that a Union rout would have occurred by 4:30 in the afternoon on July 1.)