The 118th was in camp at Falmouth until June 10 when the Army of the Potomac commenced its northward movement for the Gettysburg Campaign. The Corn Exchange Regiment acted as support in the cavalry engagements of Aldie, Upperville and Middleburg. The regiment reached Gettysburg early on July 2, 1863. At four o'clock that afternoon, the 118th went into action in support of Maj. Gen. Daniel Sickles' III Corps and was closely engaged, losing 3 killed, 19 wounded, and 3 missing or captured. On the 3rd, the regiment was moved to Big Round Top, where it remained without engagement. Following the battle, it then joined in the pursuit of the retreating Confederates and encountered the enemy on July 4.