At Gettysburg the 121st occupied an advanced position under cover of a narrow strip of woods, along which were scattered a number of large rocks. Behind these the men were comparatively safe from the fire of the enemy, and its only loss was two men wounded by stray bullets. “The next day little fighting was done on the left of the line but the culmination of the battle in the charge and repulse of General Pickett was watched eagerly by the regiment as by all the unengaged part of the army; and with infinite relief they saw the charging force, shattered and torn by shot and shell, fall back in confusion.” (B.)
The next day, the 4th of July, was dark and cloudy and the smoke of the previous day's battle settled down upon the field so as to hide the movements of the enemy, and the retreat of Lee's army was not observed. But on the 5th the Sixth Corps began the pursuit, the First Division having the lead, marching by the Fairfield road. The rear guard of the enemy was soon encountered and brisk skirmishing ensued, but no general attack was made. General Sedgwick decided to attempt to cut off the crossing of the Potomac by the enemy, by a flank movement over South Mountain and led the Corps by a steep and rugged pass