Hooker learns some Confederate camps have been abandoned.

Hooker crosses the Rappahannock in force. He proposes to attack the remaining Confederate troops; President Abraham Lincoln vetoes the plan. The Confederates do not change their plans in response to Hooker's move.

Brig. Gen. John Buford reports the Confederate cavalry to be at Culpeper.

Hooker receives reports of Confederate infantry at Brandy Station. He telegraphs Lincoln and proposes to attack at Fredericksburg and then march on Richmond. Lincoln refuses him again.

The Union War Department announces the creation of a new department, the Department of the Susquehanna, commanded by Darius Couch (lately resigned from II Corps), to contain Federal troops in eastern and central Pennsylvania; it will not be under Hooker's control.

Brig. Gen. Daniel Tyler assumes command of the Federal troops at Harpers Ferry.

Union forces recross the Rappahannock at Fredericksburg; the main body begins moving north.

Lee orders First Corps, under Lt. Gen. James Longstreet, and Third Corps, under Lt. Gen. A.P. Hill, to leave Culpeper and Fredericksburg respectively, and come north.

The last Union troops, II Corps, leave Fredericksburg.

Brig. Gen. Alfred Jenkins's cavalry brigade and Rodes's infantry division cross the Potomac. Jenkins reaches Chambersburg, Pennsylvania, and takes up defensive positions north of it.

On rumors of approaching Union infantry, Jenkins withdraws from Chambersburg, falling back to Greencastle.

4:00 p.m.: David Gregg's Union cavalry division meets Fitz Lee's Confederate cavalry brigade at the battle of Aldie. After a heavy fight, Lee withdraws to Middleburg.

8:00 p.m.: Fitz Lee encounters Union cavalry under Col. Alfred Duffie at Middleburg and fighting begins there.

Maj. Gen. John Bell Hood's and Maj. Gen. Jubal Early's divisions cancel planned advances in response to the cavalry fighting.

Hill's corps reaches Berryville.

Rodes's division enters Greencastle, the first Confederate infantry in Pennsylvania.

Jenkins fights a brief skirmish with a company of the 1st N.Y. Cavalry of Milroy's division, the first shots fired in Pennsylvania. Corporal William Rihl of the 1st N.Y. Cavalry is killed; he is the first death north of the Mason-Dixon line.

Brig. Gen. Joseph Knipe's brigade of 90-day militia withdraws from Chambersburg to Harrisburg.

Henry Halleck places under Hooker's command all troops of VIII Corps east of Cumberland, Maryland. He also gives Hooker partial, but incomplete, authority over the Washington D.C. defenses.

John Mosby passes through the Union army and observes that it is not moving, making it easy for Stuart to pass through it.

Lee receives reports that Hooker's engineers have built a pontoon bridge over the Potomac at Edwards Ferry.

Mosby reports to Stuart that the Army of the Potomac has not moved for six days, and reaching the Potomac east of the Blue Ridge will not be difficult.

Early morning: The Union Army begins marching north after a six-day halt. Hooker places Reynolds in command of the advanced wing; I Corps, III Corps, XI Corps, and Julius Stahel's cavalry division. I, III, and XI Corps cross the Potomac at Edwards Ferry (XI Corps at 3:45 a.m. the leading unit, III Corps at 6:00 p.m. the last). Robertson and Jones do not report the crossing to Lee.

Hooker orders the Harpers Ferry garrison to be ready to move to attack Lee's Potomac crossings.

Afternoon: Stuart's advance is blocked by the Federal II Corps, unexpectedly found marching north. Rather than turn back, he heads south, stopping for the night at Buckland, Virginia.

Maj. Gen. Harry Heth's and Maj. Gen. Dorsey Pender's divisions cross the Potomac at Shepardstown; Maj. Gen. George Pickett's division crosses at Williamsport.

About 12,000 men are on duty in the Department of the Susquehanna under the June 15 call; 8,000 are from New York City. In response, Governor Andrew Curtin of Pennsylvania calls for 60,000 state militia for 90 days (or the duration of the emergency if less); 24,000 respond, but none will muster in time to participate in the campaign.

Morning: Early's division burns the Caledonia Iron works, owned by Congressman Thaddeus Stevens of Pennsylvania.

Afternoon: Early, with Brig. Gen. John B. Gordon's brigade, enters Gettysburg, demands a ransom of $10,000 but does not get it. Gordon's men camp at Gettysburg that night. The rest of Early's division is marching on a parallel road north of Gettysburg.

Hood's and McLaws's divisions cross at Williamsport.

Robertson fails to bring his and Jones's brigades north into Maryland and Pennsylvania, as Stuart has ordered him to do when the Union Army is across the Potomac. Lee is left with a single cavalry brigade (Jenkins's) plus Brig. Gen. John Imboden's mounted infantry brigade.

Hooker requests permission to abandon Harpers Ferry and Maryland Heights.

Maj. Gen. William French arrives at Harpers Ferry and take command there.

Night: Stuart camps at Wolf Run Shoals on the south side of Occoquan Creek.

Maj. Gen. Isaac Trimble reports for duty; Lee sends him to join Ewell at Carlisle.

Evening: Stuart begins crossing the Potomac at Rowser's Ford in the evening.

Morning: Hooker goes to Harpers Ferry to inspect the garrison. While there he receives orders from Halleck informing him that he may not withdraw the garrison. Angered, Hooker offers his resignation as commander of the Army of the Potomac.

7:00 p.m.: The War Department sends an officer to the Army of the Potomac to relieve Hooker of command.

3:00 a.m.: Maj. Gen. George Meade, lately commanding V Corps, is put in command of the Army of the Potomac. The Union Army does not move this day while Meade takes over headquarters.

3:00 a.m.: Stuart completes his crossing of the Potomac at Rowser's Ford.

Early makes a $100,000 requisition, plus supplies, on the city of York; it is partially met and Early is satisfied.

Meade requests permission from Halleck to pull 7,000 men out of Harpers Ferry and bring them to Fredrick, leaving 4,000 in the garrison. Halleck approves the move.

Noon: Stuart captures a Union wagon train at Rockville Maryland. Chambliss's brigade pursues the retreating teamsters to within four miles of Washington. Stuart seizes 125 wagons of supplies, but they slow his march and he is only able to advance ten more miles that day, spending the night at Brookeville.

Gordon's brigade approaches the Wrightsville bridge over the Susquehanna, but Union militia burn it before it can be captured. Gordon's men help put out the fire after it spreads to the town of Wrightsville.

Evening: Ewell makes plans to attack and capture Harrisburg.

Night: Jenkins' brigade camps four miles from Harrisburg. It is as far north as any Confederate unit will get in the entire war.

Night: French reports that Harpers Ferry cannot be held by 4,000 men. Meade, without Halleck's permission, orders Harpers Ferry abandoned. Halleck approves the move after the fact.

Night: A Confederate scout named Harrison reports the movements of the Union army to Longstreet and Lee.

While planning to attack Harrisburg, Ewell is ordered by Lee to turn south and march to Chambersburg. Hill is ordered to Cashtown, two divisions of Longstreet's corps to the camp on the east side of South Mountain near Cashtown, Pickett to garrison Chambersburg until relieved by Imboden.

Lee sends a second order to Ewell about eight hours after the first, directing him to move to Heidlersburg, then to Cashtown. Unfortunately Johnson's division has already moved by way of Chambersburg, delaying its arrival at Gettysburg by several hours.

Union lead elements reach Emmitsburg and Westminster, in Maryland. Buford, with Col. Thomas Devin's and Col. William Gamble's brigades, crosses Boonsboro Pass (west to east) and Monterey Pass (west to east), camping for the night at Fairfield.

5:00 p.m.: Stuart camps for the night near Westminster. That night he learns the position of the Union army; it is much farther north than he expects, and between him and Lee, though Stuart is not aware of that.

Night: Reynolds, with I Corps and XI Corps, camps at Emmitsburg.

Morning: A battalion of cavalry attached to Early's division, marching west from York to Heidlersburg, encounters Union cavalry north of Hanover.

11:00 a.m.: Brig. Gen. J. Johnston Pettigrew's brigade, of Heth's division, approaches Gettysburg, supposedly looking for shoes. Gamble's and Devin's brigades enter Gettysburg, while Pettigrew is still a half mile away. Pettigrew, under orders not to engage, withdraws as they arrive, and returns to Cashtown.

Afternoon: Stuart's brigades advance to Hanover, where they encounter Brig. Gen. Judson Kilpatrick's cavalry division. Stuart initially captures Hanover but is driven out of it in a Union counterattack. Stuart marches away east to Dover, Pennsylvania.

Evening: Heth asks Hill's permission to go back into Gettysburg the next day with his division. Hill grants it, and informs Lee of the decision that night.

Morning: Stuart learns from Fitz Lee that Early's division has marched from York to Heidlersburg the day before; but rather than proceed there he decides to move to Carlisle, which Ewell left two days prior. The decision to move there delays his reunification with Lee for a full day.

Johnson's division, marching on the Chambersburg-Cashtown road, encounters Longstreet's corps. Johnson's division and its wagon train move to Cashtown in advance of Longstreet's corps, which waits behind.

Ewell, learning that Hill has gone to Gettysburg, orders Rodes and Early to go there as well.

Heth's division, supported by Pender's division, attacks Buford's cavalry. I Corps reinforces Buford and beats back the Confederate assault. Reynolds is killed; command passes to Maj. Gen. Abner Doubleday.

Afternoon: Maj. Gen. O.O. Howard and XI Corps arrive; Howard takes command of the Federal forces; XI Corps reinforces the Union right.

The Confederate attack resumes. Heth, Pender, and part of Rodes attack I Corps west of town, while Ewell, with Early and the rest of Rodes attack XI Corps north of town. I and XI Corps fall back to Cemetery Hill. Casualties include Maj. Gen. Harry Heth, wounded, on the Confederate side; and Brig. Gen. Francis Barlow, seriously wounded and captured, on the Federal side.

XII Corps, arriving about 5:30 p.m., takes position on Culp's Hill, bolstering the Federal right flank.

Lee orders Ewell to take Culp's Hill "if practicable"; Ewell decides it is not practicable and makes no assault.

Meade sends Hancock to take command of all troops at Gettysburg. Hancock supersedes Howard, but defers to the XII Corps commander, Maj. Gen. Henry Slocum, when Slocum arrives at 7:00 p.m.. Meade orders the entire Union Army to move up to Gettysburg.

Stuart, approaching Carlisle, finds it occupied by Pennsylvania militia under Brig. Gen. W.F. "Baldy" Smith. He shells them briefly but does not launch an attack. Major Andrew Venable of Stuart's staff meets Lee at Gettysburg.

3:00 a.m.: Meade arrives at Gettysburg in person and assumes command.

Daybreak: Captain S.R. Johnston of Lee's staff and Major J.J. Clarke of Longstreet's staff report to Lee that Little Round Top is empty and no Union troops are near it. Lee orders Longstreet to attack the Union left flank, and Ewell to attack Culp's Hill with Johnson's division as soon as he hears Longstreet's attack begin.

9:00 AM: Meade sends an aide with orders to Maj. Gen. Dan Sickles to post III Corps on the left of II Corps, reaching to Little Round Top. Sickles rides to Meade and asks how much discretion he has in placing the troops, getting a vague reply. Sickles posts his troops, rendering Captain Johnston's report out of date, but his line cannot quite reach Little Round Top.

Morning: The 3rd Maine and a detachment of sharpshooters under Col. Hiram Berdan advance into Pitzer's Wood and encounter Brig. Gen. Cadmus Wilcox's Brigade of Anderson's division moving southwards along Seminary Ridge. The resulting skirmish makes Sickles nervous about the safety of his line; Sickles asks Meade for advice but gets no helpful reply.

1:00 p.m.: Captain Johnston reports to Longstreet that his corps, advancing to attack the Union left, will be detected if it continues. Longstreet orders a countermarch; his units reach their attack positions undetected, but the countermarch delays the attack for about 90 minutes.

Afternoon: Sickles advances his line forward, cutting his connection with the rest of the Union Army.

Late afternoon: Hood's division attacks Little Round Top and the left flank of Sickles's line at 4:00 p.m. Two divisions of V Corps are sent into the fight to defend Little Round Top and reinforce Sickles's left at the Devil's Den and Wheatfield. At 5:30 p.m., McLaws attacks Sickles's front and right flank; III Corps is crushed and forced back to retreat, but reinforcements from II Corps and elsewhere hold the original line along Cemetery Ridge. Casualties include Generals Pender, Semmes, Barksdale (killed or mortally wounded) and Hood (seriously wounded) on the Confederate side; and Generals Weed, Willard, Zook (killed or mortally wounded) and Sickles (seriously wounded) on the Federal side.

Night: Johnson's division attacks Culp's Hill and is able to seize some trench lines that had been abandoned by troops sent to reinforce the Federal left; part of Early's division attacks Cemetery Hill. Union troops which had been defending Cemetery Ridge rush back to the right to repulse him.

Meade convenes a council of war. Near midnight, the council votes to stay in position and await attack one more day.

Morning: Two more Confederate attacks by Johnson's division are repulsed by the Union infantry. Following the repulse of the last, around 9:00 a.m., the Union makes some local counterattacks, retaking a small amount of lost ground.

Afternoon: Confederate artillery opens a massive bombardment against Cemetery Ridge at 1:30 p.m.. After about 90 minutes, Pickett's division, supported by Heth's division under Pettigrew and two brigades of Pender's division under Trimble, attack Cemetery Ridge and are repulsed with heavy losses. Casualties include Generals Armistead, Garnett (killed or mortally wounded), Trimble and Kemper (seriously wounded and captured) on the Confederate side, and Generals Hancock and Gibbon (seriously wounded) on the Federal side.

2:45 p.m.: Stuart's cavalry circles around the Union right and attacks Union cavalry under Gregg and Brig. Gen. G.A. Custer, but cannot break through to the Union rear.

5:30 p.m.: Kilpatrick's cavalry charges Hood's division, now under the command of Brig. Gen. Evander Law, on the Confederate right and is easily beaten back. Union Brig. Gen. Elon Farnsworth is killed in the attack.

Evening: Couch orders a brigade of cavalry of the Department of the Susquehanna, commanded by Colonel Lewis Pierce, to march from Bloody Run (modern-day Everett, Pennsylvania) to Chambersburg, to try to cut off Lee's route back to Virginia.

Night: Lee decides to retreat. Johnson's division falls back to Seminary Ridge.

Morning: Union troops from XI Corps enter Gettysburg unopposed. Meade sends his cavalry towards Cashtown, Emmitsburg, and Fairfield, hoping to intercept any retreating Confederate columns.

Lee, hoping to simplify his retreat, sends a flag of truce through the lines proposing an exchange of prisoners. Meade refuses; he has already sent his prisoners to the rear, and does not have authority to agree in any event.

Union cavalry from French's command attack Falling Waters and destroy the Confederate pontoon bridge there. It is Lee's only bridge over the Potomac.

Afternoon: Rain begins falling at Gettysburg, making further combat impossible and movement, especially on South Mountain, slow and difficult.

4:00 p.m.: Imboden's brigade, escorting the Confederate's ambulances and supply train, departs Gettysburg, headed for Chambersburg.

Evening: Union corps commanders vote 5-2 to remain in position until they are certain the Confederates are retreating, and to pursue only with cavalry if they are.

Kilpatrick's cavalry attacks Confederate cavalry guarding Monterey Pass over South Mountain, through which Lee plans to retreat; but thinks himself outnumbered and falls back.

Third Corps begins to withdraw at 9:00 p.m., followed by First Corps around 11:30 p.m.

2:00 a.m.: Second Corps begins to withdraw; mud slows their retreat, and they require 14 hours to march the nine miles to Fairfield.

Morning: VI Corps advances and finds the Confederates gone. It advances after them in the direction of Fairfield.

Brig. Gen. Hermann Haupt, superintendent of U.S. Military Railroads and West Point classmate of Meade's, arrives at Gettysburg and encourages Meade to pursue Lee. Meade refuses curtly; Haupt reports back to Halleck and Lincoln that Meade is not pursuing as rapidly as he should.

Afternoon: Meade orders the rest of the Army of the Potomac to start moving south and southeast.

Evening: VI Corps encounters Lee's rear guard, a brigade of Early's division, east of Fairfield, and fights a brief, inconsequential skirmish.

Imboden arrives at Williamsport, Maryland, and finds the pontoon bridge destroyed by high water. Heavy rain has made the Potomac unfordable.

Warren reports the results of VI Corps's advance to Meade. Meade cancels his earlier orders and sends the army towards Emmitsburg.

Evening: Buford's division attacks Imboden's brigade at Williamsport. Most of the rest of Stuart's cavalry and Kilpatrick's division join in. Union forces are repulsed, but hold Boonsboro for a Union concentration.

First Corps reaches Hagerstown.

First Corps arrives at Williamsport. Confederate wounded begin crossing the Potomac on flatboats. Confederate infantry entrenches on a six-mile line between Conococheague Creek and Falling Waters.

Meade arrives in person at Fredrick. He orders his army to move to that point, then to cross South Mountain and catch Lee before he can recross the Potomac. French sends a brigade to reoccupy Maryland Heights.

Afternoon: Meade brings the Army of the Potomac forward from Boonsboro into contact with Lee's army.

Afternoon: Rain resumes falling.

Evening: Meade calls a council of war; his corps commanders vote 5-2 not to attack Lee's line at Falling Waters.

Afternoon: Heavy rain begins falling and the Potomac begins to rise again, but Second Corps is able to complete its crossing.

11:00 a.m.: Buford's and Kilpatrick's cavalry divisions attack Heth's infantry division, the Confederate rear guard. Brig. Gen. Johnston Pettigrew is mortally wounded, and the Yankees take 300 prisoners. The campaign is over; the Union army does not cross the Potomac until July 17.