According to official records, the Gettysburg campaign of 1863 began on June 3rd and ended on August 1st. No effort will be made to describe the movements, counter-movements, and fifty minor engagements that occurred before the armies crossed the Mason and Dixon’s line and finally concentrated at Gettysburg, where they engaged in battle on July 1st, 2nd, and 3rd. It is necessary, however, that the visitor should understand the approach to the field. Location of the Armies. On June 3rd the Union Army, called the Army of the Potomac, lay at Falmouth, Va., on the north side of the Rappahannock River, Major-General Joseph Hooker in command. The Confederate Army, called the Army of Northern Virginia, occupied the south bank, with headquarters at Fredericksburg, General Robert E. Lee in command. Both armies were resting after the major engagement at Chancellorsville, in which the Confederates were victorious. The Army of the Potomac was made up of seven infantry and one cavalry corps. It numbered at the time of the battle approximately 84,000. The Army of Northern Virginia was made up of three infantry corps and one division of cavalry. It numbered at the time of the battle about 75,000. Following the text is a roster of officers, which should be consulted, both for an understanding of the battle and because of the obligation to honor brave men. General Lee’s Plan. During the month of May, General Lee visited Richmond to discuss with the Confederate government various plans involving political and military considerations. Up to this time, the South had won the major victories, but her resources, both in men and sinews of war, were diminishing, and a prolonged conflict would be disastrous. It was decided that the army should invade the North via the Shenandoah and Cumberland valleys, with Harrisburg as an objective. This route not only afforded a continuous highway but put the army in a position to threaten Baltimore, Philadelphia, and Washington from the north. The Blue Ridge Mountains to the east would screen the advance, and the rich agricultural section would furnish supplies of food and forage. The time was propitious. General Lee’s army was in the prime of condition. The North was discouraged by losses, distrustful of Lincoln, weary of war. The South believed that one great victory would assure her the friendliness of the leading powers of Europe. Her independence once acknowledged, she could import the materials of war and the necessities of life which she lacked. It was thought certain that at the prospect of invasion the North would withdraw troops from the siege of Vicksburg then being conducted by General Grant. With high hopes the march was begun. Lee’s First Movement.