Before the battle of Gettysburg, on June 29th, 1863, General Reynolds issued orders to his division commanders. They were to begin their march from Frederick, Maryland at 4:00 a.m. marching to the Mason Dixon Line to the small town of Emmitsburg for a total distance of about 25 miles. The 1st Corps marched in the following order: The Second Division, the Third Division, the First Division, by Lewistown and Mechanicstown to Emmitsburg, keeping to the left of the road from Frederick to Lewistown between J. P. Kramer's and where the road branches to Utica and Creagerstown, to enable the Eleventh Corps to march parallel to it. The Eleventh Corps under the command of General Oliver Howard marched through Creagerstown via Utica Post Office as they marched from Frederick, Maryland to Emmitsburg.

As General Reynolds and his staff approached Emmitsburg that evening, General Reynolds rode ahead of his columns and entered the town. Once there, Reynolds and his staff tried to recruit locals to cross over the Catoctin Mountain Gaps to observe and report in detail the movements of the Confederate Army. General Reynolds also placed a company of Signal Corps on the mountain behind Mount Saint Mary’s College. A battery of artillery was held in Emmitsburg as reserves on the heights toward Thurmont.

General Reynolds set up his headquarters in Emmitsburg and directed Union efforts from Emmitsburg’s Lutheran parsonage, St. Joseph's Rectory, and the present day funeral home. As the First Corps marched past Mount Saint Mary’s College, Dr. Moore recalled: "The Army of the Potomac was truly a beautiful sight" and describes as grand but horrible the passing of "the wagons, ambulances, cannons, etc, which were coming early dawn till nightfall. ... They camped around Emmitsburg. Their campfires, as viewed from the college windows, almost led one to imagine that this section for miles had received in one shower all the stars of the heavens."

The Union forces, tired from a day's march from Frederick and Middletown, Maryland set up camp in Emmitsburg. The soldiers' campsite covered the grounds of the present day National Fire Academy and reached almost to what is now the Post Office. The town’s residents welcomed the men in blue. After seeing the damage done by the fire on June 15th, the men in blue thought that the rebel army had torched the town. They soon found out that it was actually a stable fire that caused three sections of the town's square to burn down and the rebels were cleared of this false accusation.

At the Southern end of Emmitsburg, toward Mount Saint Mary's College, the 11th Corps, made their way into Emmitsburg. General Howard made temporary headquarters at Mount Saint Mary's. As the rear of the 1st Corps marched out of Emmitsburg, regiments of the 11th Corps started to lay camp on the grounds of Saint Joseph’s Academy. General Howard made his headquarters at a place called Tollgate Hill at the Saint Joseph’s Rectory. Reverend Francis Burlando handed over his own quarters to General Howard without any complaint. The officers went to St. Joseph’s where the Sisters of Charity supplied them with a good dinner that was truly enjoyed. While relaxing, General Carl Schurz commander of the 3rd Division of the 11th Corps performed a small recital on the academy’s chapel organ.

Major Frederick Winkler served in the 26th Wisconsin Infantry and was part of General Schurz’s staff during the Gettysburg Campaign remembered Emmitsburg: “We marched over twenty miles and it rained. We arrived at Emmetsburg at 6:00 p.m. and, after we had located our troops here, about a mile from the village, and attended to other necessary business, General Schurz and some of us rode through the village. The 1st Corps was just passing through and there was a good deal of enthusiasm displayed. A large portion of the place is in ruins, having been destroyed by fire; expensive buildings of the Catholic Church, convents, etc., occupy very fine grounds on the limits of the place; not far from here too, at the foot of the mountains, there is Saint Mary's College, said to be the oldest college in the country.”

During the evening of June 30th, General David Birney commanding General Sickles’ Third Corps, 1st Division took up camp about a mile and a half from Emmitsburg marching from Taneytown around 3 p.m. where it was bivouacked. As soldiers of Birney’s Division encamped near Saint Joseph’s, General (then Colonel) Philippe Regis de Trobriand, commander of the 3rd Brigade of Birney’s Division received a very triumphant welcome by the residents of Emmitsburg. These men marched through the streets as women cheered and waved their handkerchiefs and the men were standing in the doorways waving their hats.

Trobriand wrote about his stay near Saint Joseph's during the evening of June 30th: “There is a large convent at Emmitsburg, with which is connected a school for young ladies, which has a reputation extending throughout the United States. It was on the domain of St. Joseph that I had placed my brigade. A small stream made part of the boundary line. I leave it to you to guess if the good sisters were not excited, on seeing the guns moving along under their windows and the regiments, bristling with bayonets, spreading out through their orchards. Nothing like it had ever troubled the calm of this holy retreat.

This same evening the First Corps was ordered to proceed to Marsh Creek located about four miles from Emmitsburg and reset camp there. Shortly after the orders were given, a disturbance broke out when soldiers of the 76th New York were told to wait until the next day to receive their pay. As they marched through Emmitsburg a soldier and later historian of the 12th Massachusetts Volunteers recorded a story about a young boy from Emmitsburg, Maryland. Later in life he wrote: “An instance of the bravery of a 15 year old Emmetsburg lad named J. W. Wheatley, as Baxter’s brigade was marching through Emmetsburg it was followed by the village boys, one of whom continued to the camp at Marsh Creek, where he offered to enlist. His offer, however, was ridiculed, and he was sent away."

"On the morning of the 1st of July he reappeared, and so earnestly entreated the colonel of the Twelfth Massachusetts to be allowed to join his regiment, a captain of Company A was instructed to take him on trial for a day or two. When the regiment halted near the seminary, the boy was hastily dressed in a suit of blue. He fought bravely until a bullet striking his musket split it in two pieces, one of which lodged in his left hand and the other in his left thigh. The boy was taken to the brick church in the town to be cared for, but nothing was afterwards seen or heard of him until July 4th. I saw him for the last time bitterly crying for his mother and sundry of other relatives. He was never mustered into the service, therefore fought as a civilian."