The first four days of July 1863 produced the strategic turning point of the war. On the 3rd of July, the Confederate Army of Northern Virginia under Robert E. Lee delivered, and saw destroyed, Pickett's Charge on the third day of the Battle of Gettysburg — the costliest single Confederate assault of the war, with approximately 6,500 casualties from the 12,500 men who advanced. On the 4th of July, the Confederate garrison of Vicksburg, Mississippi, under Lieutenant General John C. Pemberton, surrendered to Grant's army after a 47-day siege. The two surrenders, falling in the same week, together broke the Confederate strategic position in both theatres: the Mississippi River was now Union-controlled from source to mouth, the western Confederate states (Texas, Arkansas, western Louisiana) were severed from the eastern Confederacy, and Lee's army — having failed in its second invasion of the North — would not undertake another strategic offensive. The Confederacy would fight on for nearly two more years, but the strategic question had been substantially answered.
Chancellorsville and the prelude
The spring of 1863 had opened with the Battle of Chancellorsville (1st-4th of May), Lee's most famous tactical victory. Joseph Hooker's Army of the Potomac of approximately 130,000 men was outmanoeuvred by Lee's 60,000 through a celebrated flank march by Jackson's corps around Hooker's right wing, which was driven back through the Wilderness on the 2nd of May. Jackson was mortally wounded that evening by friendly fire from his own pickets and died of pneumonia eight days later — the most consequential Confederate command loss of the war. Hooker withdrew across the Rappahannock on the 6th of May. The casualties at Chancellorsville (17,300 Union to 13,300 Confederate) were heavy enough that, combined with the loss of Jackson, the Confederate victory was Pyrrhic in its strategic implication.
Lee, reorganising his army into three corps under Longstreet, Ewell and A.P. Hill, planned a second invasion of the North. The strategic objectives: to relieve Virginia of the burden of supplying both armies (the Maryland-Pennsylvania farmlands would supply the Confederate one); to influence Northern public opinion against the war in the run-up to the 1864 election; and to make possible the political settlement that the Confederate government still hoped — incorrectly, by mid-1863 — that European powers might broker. The Army of Northern Virginia crossed the Potomac into Maryland and Pennsylvania across June 1863. Hooker, having lost Lincoln's confidence, was replaced on the 28th of June by George Meade, a competent Pennsylvanian corps commander who had three days to prepare for a major engagement against an army he had not previously commanded.
Gettysburg
The Battle of Gettysburg developed by accident from a meeting engagement on the morning of the 1st of July 1863, when Confederate troops marching east in search of shoes (the Gettysburg story has acquired the legend of the shoes) encountered Union cavalry pickets under John Buford on the McPherson Ridge west of the town. Buford held the ridge through the morning, allowing the Union First Corps to come up by midday; the Confederate attack on the afternoon of the 1st of July, in which the divisions of Heth and Rodes broke the First and Eleventh Corps and drove them through the town to the high ground south of Gettysburg, was a clear Confederate tactical victory of the first day. But the Union army's high ground — the line of Cemetery Hill, Cemetery Ridge, and Little Round Top, running south from the town in a fishhook shape — was the strongest defensive position of the eastern theatre, and Meade reinforced it through the night.
The second day, the 2nd of July, produced the famous defensive stands at Devil's Den, Little Round Top, the Wheatfield, and the Peach Orchard, as Longstreet's corps attacked the Union left flank in echelon from south to north. The fighting on Little Round Top — the small hill at the southern end of the Union line, held by Colonel Joshua L. Chamberlain's 20th Maine in a famous bayonet charge — has become the most-narrated episode of the battle, partly because Chamberlain wrote vividly about it after the war and partly because Michael Shaara's 1974 novel The Killer Angels made it the central scene of the most successful Civil War fiction. The Union line held. The fighting on the second day was as costly as the first; combined casualties for the first two days were approximately 30,000.
The third day, the 3rd of July, was Lee's decision. Convinced that the Union flanks were holding because the centre had been weakened by the previous day's troop transfers, Lee ordered an assault on the Union centre by the divisions of Pickett, Pettigrew and Trimble — approximately 12,500 men advancing across three-quarters of a mile of open ground against entrenched Union infantry and artillery. Longstreet, who was to direct the assault, opposed the order and is recorded as having said simply "General, I have been a soldier all my life... it is my opinion that no fifteen thousand men ever arrayed for battle can take that position." The assault, preceded by a two-hour artillery bombardment that did limited damage to the Union centre, advanced at approximately 3.00 p.m. and was broken by Union artillery and rifle fire within an hour. Approximately half the attacking force was killed, wounded or captured. Lee met the survivors at the bottom of the slope and said, repeatedly, "It is all my fault." The Confederate retreat across the Potomac began the next night. Meade did not aggressively pursue. Lee escaped back to Virginia.
Casualties at Gettysburg: approximately 23,000 Union, 28,000 Confederate, combined approximately 51,000 in three days. The largest casualties of any battle of the war.
Vicksburg
The Vicksburg campaign in the western theatre, conducted by Grant across the first half of 1863, was militarily the most accomplished operational achievement of any Civil War commander on either side. Grant's army had spent the winter of 1862-63 in a series of unsuccessful attempts to bypass the Vicksburg fortress on the Mississippi (the canal-cutting and bayou-traverse schemes) before adopting, in April 1863, a decisive plan: to cross the Mississippi below Vicksburg, swing east into Mississippi, defeat the Confederate field armies in the state, and besiege Vicksburg from the landward side. Grant's army crossed the river on the 30th of April, conducted five successful battles across the next eighteen days (Port Gibson, Raymond, Jackson, Champion Hill, Big Black River) against superior aggregate Confederate forces, and besieged Pemberton's army of 30,000 inside Vicksburg from the 18th of May.
The siege ran for 47 days. The Confederate civilian population of Vicksburg endured artillery bombardment, scarcity of food, and the eventual reduction to mule meat and rats. The surrender on the 4th of July 1863 transferred Vicksburg, the garrison of 29,500 men, and effective Union control of the Mississippi River to the United States. The fall of Port Hudson, the remaining Confederate Mississippi fortress, followed on the 9th of July. Lincoln's celebrated assessment — "The Father of Waters again goes unvexed to the sea" — was, with the qualifier of guerrilla operations on the Louisiana-Arkansas bank, substantially correct from that date forward.
The strategic consequence
The combined effect of Gettysburg and Vicksburg was that the strategic question had been substantively resolved by mid-July 1863. The Confederate strategic options for victory — invasion of the North, foreign intervention, exhaustion of Union public opinion — were all in decline. The military problem of the remaining twenty-one months of the war was the question of how long it would take Union armies to grind down the Confederate resistance through attritional campaigns in Virginia (Lee against Grant from May 1864) and Georgia (Sherman against Johnston/Hood from May 1864). The final phase of the war is the next chapter.
End of Chapter VI