On June 15th, 1863, the first portions of General Robert E. Lee's Army of Northern Virginia began crossing the Potomac River near Hagerstown, Maryland. At this time the Union Army of the Potomac under General Joseph Hooker was still in Virginia could not pinpoint General Lee's exact location, as he had used South Mountain as cover to screen his movements. The first thing that General Hooker needed to do was seize the mountain passes of South Mountain. But unknown to General Lee, Union scouts had seen his movements in Maryland as early as June 17th. Because of this General Hooker started to develop a plan of attack.

Confederate General Albert Jenkins’ Cavalry Brigade was the first to cross the Potomac River on the 15th of June, securing the way for General Richard Ewell’s Corps. Once the First Maryland Cavalry had safely crossed the Potomac River, General Ewell ordered them to Frederick to destroy the iron railroad brigade at Monocacy. The Marylander's crossed South Mountain at Tuner's Gap and entered Frederick where they were met by heavy resistance from a Federal Cavalry force. After a spirited skirmish, the Marylander's briefly occupied Frederick. After it was known that his force could not destroy the iron bridge, Gilmore pulled his Maryland Cavalry back. The Marylanders re-crossed Turner's Gap and made it safely to Hagerstown.

Because of the Confederate Army activity in the Cumberland Valley as well as in Frederick, during the morning of June 18th, General Hooker requested that a signal station to be built at Crampton's Gap on South Mountain for observation and communication. General Hooker also asked for cavalry support that was near Harper's Ferry to seize all mountain gaps from Maryland Heights to Boonsboro. General Robert Cumming Schenck, commanding the Middle Department in Maryland received General Hooker's request to spare a portion of his artillery, infantry, and cavalry, to seize and hold the South Mountain passes, as well as holding Maryland Heights and the passage via Sandy Hook. This is in preparation of the Union Army entering Maryland and a way to protect Washington as well as a Baltimore.

On June 19th, General Hooker ordered General Samuel Peter Heintzelman commander of the Department of Washington who was at Poolesville to help seize the mountain gaps on South Mountain. General Heintzelman's force consisted of 1600 infantry, one battery and five troops of cavalry. Realizing that his line would be stretched too thin, General Heintzelman wrote to General Hooker and asked him if General Schenck's forces at Harper's Ferry could hold South Mountain as the mountain range was in the Middle Department under his command. General Hooker was forced to operate without General Heintzelman's support and manpower.

When Brigadier General Albert G. Jenkins with 1,500 cavalry entered Pennsylvania, he had sent several regiments of his brigade on missions to destroy the vital transportation brigades and communications around the Chambersburg area. On June 19th, Company D of the 14th Virginia Cavalry was ordered to Waynesboro, Pennsylvania to capture horses and cattle for the army. A powerful thunderstorm surprised them during the night, and they were forced to take refuge on a large farm. While they took up refuge on the farm, the farmer was obligated to furnish them with rations.

The next day the men were foraging and around noon Company D came upon the farm of an old Pennsylvania German. According to Lieutenant Herman Schuricht; "He was scared to death at catching sight of us, and shouted "O mein Gott, die rebels!" I soon reassured him, telling him that no harm should result to him if he furnished us with a dinner and rations for our horses, and we were well cared for. A Federal cavalry regiment passed in sight of the place, fortunately not discovering our presence, and I concluded to march with my company to Lesterburg, [Leitersburg] Md., where the citizens furnished us with supper. We camped for the night in an open field, midway between Lesterburg [Leitersburg] and Hagerstown."

On June 21st, General Jenkins started out for Chambersburg again after hearing reports that no Federal soldiers had occupied the city. General Jenkins’ took two companies of the 14th Virginia Cavalry and charged into Chambersburg at night. Captain Moorman's Company of the 14th Virginia Cavalry was ordered to proceed to South Mountain and capture horses, then pass through Leitersburg and enter the mountain region. At 11 o'clock at night the company came to Use's Iron-Works. Mr. Use, upon demand furnished provisions to the troopers. Unfortunately, Mr. Use secretly informed the farmers in the area and warned the Federal troops of their approach.

On June 22nd a skirmish erupted at Monterey Pass near the Mason and Dixon Line of South Mountain as Company D of the 14th Virginia Cavalry of General Albert Jenkins' Brigade ran into an armed militia of Captain Robert Bell's 21st Pennsylvania, Captain David Conaughy's Home Guard and a detachment of 1st Troop Philadelphia City Cavalry under Captain Samuel Randall. Confederate skirmishers scoured the woods on foot on each side of the Emmitsburg and Waynesboro Turnpike. When the Federal cavalry left, the Confederates reached Monterey Springs and continued firing at several bodies on horseback to enter Fairfield at dusk encamping in the area. This was the first fight that took place on South Mountain during the Pennsylvania Campaign.

The next day on the June 23rd, Schuricht’s detachment of the 14th Virginia Cavalry started out by dawn, capturing several horses in the Cashtown area. By 2 P.M. in the afternoon, a detachment of the 14th Virginia Cavalry headed toward Caledonia Iron Works, west of Gettysburg. They were pursuing a small detachment Union cavalry. Roughly two miles past Caledonia, the detachment of Confederate Cavalry saw that the Federal troops detachment had blockaded the road.

Lieutenant Herman Schuricht of Company D noted that he was ordered by Major Bryan to approach the barricade with nine men. Lieutenant Schuricht directed four men to approach the barricade to the right of the road, while Lieutenant Schuricht and the rest of men took to the left of the road. About 25 Union men were waiting in ambush and disappeared as Lt. Schuricht drew nearer. The barricade was quickly removed while Captain Moorman charged, with 25 men in pursuit of the Yankees. Lieutenant Schuricht soon followed in the chase.

The Federal detail took refuge behind a company of Union cavalry that was in the woods. The Federal cavalry turned their horses as the 14th Virginia Cavalry came upon them. Shots rang out striking Private Eli Amick of the 14th Virginia. Soon afterwards, Major Bryan called off the pursuit and returned to Caledonia Iron Works. The 14th Virginia Cavalry traveled back to Greenwood where their rear guard was located.

On June 23rd and 24th, General Hooker requested to have more Federal troops in possession of South Mountain and Hooker's orders were being carried out by General William French commanding the military district of Harper’s Ferry, as Union scouts were overlooking and watching the Cumberland Valley as well as Pleasant Valley.

Further to the south early during the dawn hours on June 25th, at Edward’s Ferry, General Joseph Hooker’s Army of the Potomac began to cross the Potomac River entering Maryland. Leading the way was General Oliver O. Howard’s Corps who marched crossed the Potomac River on two 1,400-foot-long pontoon bridges. Heavy rains during those three days made the single road to and from the bridges extremely muddy as they began to march toward Poolesville.

Confederate General Jubal Early entered Pennsylvania on June 23rd via the road from Smithsburg marching toward Waynesboro. Once at Waynesboro, General Early’s Division encamped and took up the march northward on Black Gap Road. He traveled passed the little towns of Quincy, Mont Alto that sit at the western base of South Mountain, and arrived at Black Gap. General Early and his Division changed directions heading East on the Chambersburg Pike moving toward Gettysburg. On June 26 East of Black Gap, General Early’s troops burned the ironworks at Caledonia. These ironworks belonged to Congressman Thaddeus Stevens, whose radical antislavery views were widely known.

As General Early came upon Cashtown Gap, he came to a fork in the road to the right the road was called the Cashtown Road while the one on the left was called Hilltown Road. General Early himself took the road on the left splitting his command into two columns. A local family bible of a tavern once owned by John Harding explains that General Early passed the property, and un-mounted from his horse stepping on a rock near the front door and walked in side. There he saw several ladies drinking tea and started to talk to them. General Early noticed a map on the wall of Adams County Pennsylvania. He took his knife, and cut the canvas map out and stuck it in his pocket. General Early said, "I need this more than you do." General Early then remounted his horse and started to the head of his command.

Once his division had passed through the South Mountain pass of Cashtown on June 26th, one of the local citizens shot a Confederate soldier. General Early became outraged by this act and ordered the bushwhackers to be found. He even threatened to burn the town of Cashtown in order to bring justice for the shooting of one of his men. However, the accusing party was never found and Cashtown was never burned.

Read part 2: The Union makes ready