Three miles (4.8 km) west of town, about 7:30 a.m., Heth's two brigades met light resistance from cavalry vedettes and deployed into line. Eventually, they reached dismounted troopers from Col. William Gamble's cavalry brigade. The first shot of the battle was claimed to be fired by Lieutenant Marcellus E. Jones of the 8th Illinois Cavalry, fired at an unidentified man on a gray horse over a half-mile away; the act was merely symbolic.^[4] Buford's 2,748 troopers would soon be faced with 7,600 Confederate infantrymen, deploying from columns into line of battle.^[5]

Gamble's men mounted determined resistance and delaying tactics from behind fence posts with rapid fire, mostly from their breech-loading carbines. While none of the troopers were armed with multi-shot repeating carbines, they were able to fire two or three times faster than a muzzle-loaded carbine or rifle with their breechloading carbines manufactured by Sharps, Burnside, and others.^[6] Some troopers in the brigade commanded by Brig. Gen. William Gamble had Spencer repeating rifles. The breech-loading design of the carbines and rifles meant that Union troops did not have to stand to reload and could do so safely behind cover. This was a great advantage over the Confederates, who still had to stand to reload, thus providing an easier target. But this was so far a relatively bloodless affair. By 10:20 a.m., the Confederates had reached Herr Ridge and had pushed the Federal cavalrymen east to McPherson Ridge, when the vanguard of the I Corps finally arrived, the division of Maj. Gen. James S. Wadsworth. The troops were led personally by Gen. Reynolds, who conferred briefly with Buford and hurried back to bring more men forward.^[7]