The positions of both the Federal 'Army of the Potomac' (AoP) and the Confederate 'Army of Northern Virginia' (ANV) as LEE's forces invade south-central Pennsylvania. While the Confederate III Corps has already moved well up the Cumberland Valley, the AoP concentrates near Washington, unsure of LEE's intentions and protecting the capitol.

Confederate II Corps, moving up Virginia's Shenandoah Valley as the Army of Northern Virginia's vanguard, surprises Union General MILROY's 2nd Division, fortified in the town of Winchester. Confederate General Jubal EARLY's Division advances on the town from the south pushes Union forces off Pritchard's Hill, but is blocked from Winchester by Federal resistance and the supporting cannons from the forts.

In an effort to overcome Federal resistance in Winchester, based on major fortifications to the north of that town, Confederate General EARLY's Division executes a lengthy flanking march and emerges just to the west of the union strongpoints. The sudden appearance the Confederate division surprises Union General MILROY who assumes that EARLY's force is still deployed next to General JOHNSON'S Division, to the south of Winchester.

While looking for the Army of Northern Virginia, Confederate General STUART's Cavalry Division encounters Union Genral KILPATRICK's 3rd Cavalry Divison outside of Hanover, Pennsylvania, blocking their way. The confederate cavalry attacks, penetrating the town, but is driven back as the Northen cavalry regain their balance, dig in and reinforce. Traffic problems and other commitments inhibit STUART's ability to reinforce his lead brigade.

Once LEE learns that the Army of the Potomac is closer than he thought, he orders his II Corps to pull back from the Susquehana river and to concentrate around Cashtown. his cavalry commander, General STUART, is absent (looking for LEE), preventing LEE from forming a clear picture of Federal dispositions.LEE's I and III Corps prepare to move through the mountains from Chambersburg, believing the enemy to be far away. Meanwhile, Union Genral BUFORD's 2nd Cavalry Division occupies Gettysburg, well aware of LEE's movements and prepares to defend the crossroads. General MEADE, aware of the ituation, orders his corps to concentrate on Gettysburg the next day

Confederate General LEE's appreciation of the Federal position facing him early on 2 July was deeply flawed, for lack of cavalry. Based on his misapprehension of the Federal line, he proposed a shallow flanking attack against what he believed to be the exposed left wing of the Union forces present along the Emmitsburg Road. In actuality, the Federal positon was further East, along Cemetery Ridge.

LEE starts the retreat of the Army of Northern Virginia 5 July, but MEAD doesn't start his Army of the Potomac moving until the next day. By 6 July, the ANV has crossed into the Cumberland Valley, screened by his cavalry. The first Federal reaction is to send the Cavalry Corps to the Potomac Crossings to try and black the Confederate retreat.

By 12 July, the Army of Northern Virginia was virtually trapped against the rain-swollen Potomac River. LEE dug in and waited for the river to become fordable. MEADE deployed his army, but was reluctant to attack his still-dangerous enemy in such a strong position. The attack was postponed from 13 July to 14 July.

By 25 July, LEE had managed to bring his badly bruised Army of Northern Virginia back to when the campaign had begun. In doing so, he avoided being trapped by numerous Federal efforts. By 25 July, both armies were eyeing one another, waitnign for the next move.