Union Colonel Freeman McGilvery had already ordered several batteries to support Major General Sickles collapsing line. Although the men of the 3rd Corps tenaciously fought to hold their ground, they could not halt the irresistible waves of gray-clad Southern soldiers pouring towards them from south and west. Brigadier Generals Barksdale and Wofford lead their veterans hoping to crush the slowly retreating federals in their front.

Colonel McGilvery watched as the Union infantry gave way to the surging gray tide. Of this days events he would report, "At about a quarter to 6 o'clock the enemy's infantry gained possession of the woods immediately on the left of my line of batteries, and our infantry fell back both on our right and left, when great disorder ensued on both flanks of the line of batteries. At this period of the action, all of the batteries were exposed to a warm infantry fire from both flanks and front, whereupon I ordered them to retire 250 yards and renew their fire." [5]

Through the fields between the Peach Orchard and the Trostle Farm Homestead, Captain John Bigelow's 9th Massachusetts battery retired by the recoil of his guns. Realizing that he could not limber up to withdraw without being overrun, the men of the 9th straightened the guns with each discharge hoping to keep the advancing Confederates, especially the relentless 21st Mississippi, at bay. Upon reaching the Trostle Farm buildings, they backed up towards a stone wall, firing at the enveloping line of butternut and gray. Despite risking piling their ammunition near the gun barrels for faster loading, the game union cannoneers could not hold back the veteran Southerners much longer. Men and horses seemingly fell every second. [C]

Looking behind him to Cemetery Ridge, Colonel McGilvery realized that the men pulled to support General Sickles had left a huge gap in the Federal's line. If no infantry could not hold this line, artillery alone would need to accept the challenge. As the Colonel reported, "The crisis of the engagement had now arrived. I gave Captain Bigelow orders to hold his position as long as possible at all hazards, in order to give me time to form a new line of artillery, and justice demands that I should state Captain Bigelow did hold his position and execute his firing with a deliberation and destructive effect upon the enemy in a manner such as only a brave and skillful officer could, until-one officer killed and the others wounded, and more than half his men either killed or wounded, and his horses all shot down at the limbers-he was forced to leave four guns and retire." Captain Bigelow's 9th Massachusetts gave Colonel McGilvery the time he needed. "In the meantime I formed a new line of artillery about 400 yards to the rear, close under the woods, and covering the opening which led into the Gettysburg and Taneytown Road "

The Union line on Cemetery Ridge now patched together, the 21st Mississippi kept surging forward. Having captured four of the 9th Massachusetts's guns, the hardy Southerners wanted more. Lead by Colonel Benjamin G. Humphreys, the Butternuts pushed past the Trostle Farm, captured the guns of Battery I, Fifth US Regulars, and looked towards the prize of Cemetery Ridge. Successful beyond all expectations except for possibly their own, Colonel Humphreys however realized that they had surged beyond their supports. Now, the Confederate Colonel would turn to see fields behind him and on either side empty of men in gray except for him own brave soldiers. Grudgingly, he ordered his men to withdraw to the safer ground near the Trostle Farm, giving up the ground and guns he and his men fought so hard to obtain. They had lost much of what they had gained except the knowledge that they did their duty with exceptional courage and determination.

At day's end, Colonel McGilvery would conclude, "On July 2, where the battle raged most furiously, part of the Fifth and Ninth Massachusetts, and C and F, consolidated Pennsylvania Artillery, contested every inch of ground, and remained on the field to the very last. The Sixth Maine Battery came into action in very opportune time, and rendered very valuable service. Captain Irish, of battery F, Pennsylvania Artillery, acting volunteer aide to me was hit on the thigh in the early part of the engagement by solid shot, but would not leave the field to have his wound dressed until ordered by me to do so, and, notwithstanding a serious contusion which he was suffering under, reported to me on the morning of July 3, and remained with me during the day, ready to discharge any duty. Captains Phillips' and Bigelow's conduct was gallant in the extreme." [5]

See also McGilvery's line along Cemetery Ridge.