The Great Battle of Gettysburg
As Gettysburg hits 150, a detailed account of the nation’s greatest battle.


Mackubin Thomas Owens

Robert E. Lee’s smashing victory against Major General Joseph Hooker’s Army of the Potomac at Chancellorsville in May 1863 provided the Confederacy with three strategic options: shift resources from Virginia to Mississippi in order to revive Vicksburg, the Rebel redoubt on the Mississippi River; reinforce Braxton Bragg’s Army of Tennessee, enabling him to reprise his 1862 invasion of Kentucky and maneuver the Union Army of the Cumberland under William Rosecrans out of its position in central Tennessee; or invade Pennsylvania. 


But after Chancellorsville, it was probably too late to affect the outcome at Vicksburg, because the siege was already under way. (Vicksburg would fall on the Fourth of July.) And it didn’t make sense to detach forces from the Confederacy’s only successful field army, the Army of Northern Virginia, under its only successful general, Lee, and send them to other generals whose competence was questionable. In the end, Lee effectively made the case to Confederate president Jefferson Davis that the best use of limited Confederate resources was to invade Pennsylvania. As he had done in the fall of 1862, Lee intended to effect a strategic turning movement, draw the Yankees out of Virginia, and annihilate a Federal army on Union soil, forcing Lincoln to sue for peace.

After the Seven Days’ Battles on the Virginia Peninsula in June 1862, Lee had organized his Army of Northern Virginia into two corps, the first commanded by General James Longstreet and the second by General Thomas Jonathan “Stonewall” Jackson. After Jackson’s death at Chancellorsville, Lee reorganized the army into three corps: I Corps under Longstreet, II Corps under James Ewell, and III Corps under Ambrose Powell Hill. The latter two had been excellent division commanders. However, their elevation to corps command was an example of the “Peter Principle” at work: promotion to a level above one’s competence. Lee would sorely miss Jackson in Pennsylvania. 

The Campaign Begins

On June 3, Lee slipped out of his base at Fredericksburg and headed west into the Valley of Virginia. Ewell led the way, with Hill and Longstreet in trace. Unsure of Lee’s intentions, General Joseph Hooker, commanding the Union Army of the Potomac, ordered his cavalry commander, General Alfred Pleasonton, to conduct a reconnaissance across the Rappahannock. On June 9, Pleasonton’s cavalry surprised Jeb Stuart at Brandy Station. The ensuing battle was the largest all-cavalry engagement of the war. Although the Yankees were eventually driven from the field, the battle embarrassed Stuart. It also illustrated the strides made in the quality of Union cavalry under Hooker. But perhaps most important, it alerted Hooker to Lee’s movement north. 

On June 13, Hooker began to move north in an attempt to keep his army between Lee and the Federal capital. The next day, Ewell routed a Federal force at Winchester, and on June 15, Lee crossed the Potomac. During his 1862 invasion of Maryland, Lee’s operational plan had been disrupted by unexpected resistance on the part of the Union garrison at Harpers Ferry. This time, Lee ignored it, heading directly north from the Shenandoah Valley into the Cumberland Valley of Maryland west of South Mountain.

From the beginning of the campaign, Lee was unsure of the precise location and disposition of Hooker’s army. Stuart’s cavalry was supposed to provide such information, screening Lee’s advance into Pennsylvania, operating east of Blue Ridge between Lee and Hooker, and finally reuniting with Lee around York, Pa. Unfortunately for Lee, the encampment of the Army of the Potomac lay astride the route Stuart was to follow, forcing the latter to swing farther to the east, thereby placing Hooker between Lee and Stuart’s cavalry, which could not provide Lee with the location of the Union army.

For the next week, Stuart was unable to “turn the corner” because the Army of the Potomac was moving much faster than it had in the past. The main reason for this was that Hooker had reduced its baggage train. 

On June 28, Hooker threatened to resign if his demand to assume control of the Harpers Ferry garrison was rejected. The general in chief, Henry Halleck, accepted Hooker’s resignation, much to the latter’s surprise, and replaced him with George Meade, a Pennsylvanian who had formerly commanded the Union V Corps.

All Roads Lead to Gettysburg

A glance at a map of south-central Pennsylvania reveals that “all roads lead” to Gettysburg. The town resembles the hub of a wheel with spokes converging from all directions: from the southwest, the Hagerstown Road; from the northwest, the Cashtown Pike; from the north-northwest, the Mummasburg Road; from the north, the Carlisle Road; from the northeast, the Harrisburg Road; from the east, the Bonaughtown Road and the York Pike; and from the south, the Emmitsburg Road, Taneytown Road, and Baltimore Pike.

Each of the two armies was operating in ignorance of the other’s location, but on June 30, Lee ordered Ewell to move south from Carlisle, and Hill to move east from Cashtown. 

Meade’s plan was to assume a defensive position behind Pipe Creek in Maryland, just south of the Pennsylvania line. But Major General John Reynolds, commanding the Army of the Potomac’s I Corps, ignored the “Pipe Creek Circular” and moved northeast to occupy Gettysburg. The earliest Reynolds could do so was mid-morning of July 1, so on the evening of June 30, John Buford’s cavalry division moved into position on the high ground west of town to hold on until Reynolds’s arrival.