The two great armies were scattered over portions of Maryland and southern Pennsylvania. Both were marching northward along parallel lines, the Federals endeavoring to stay between Lee's army and Washington. It was plain that they must soon come together in a gigantic conflict; but just where the shock of battle was to take place was yet unknown.
Meade sent General Buford in advance with 4,000 cavalry to intercept the Confederate advance guard.
On the night of June 30th Buford encamped on a hill a mile west from Gettysburg, and here on the following morning the great battle had its beginning.
On the morning of July 1st the two armies were still well scattered, the extremes forty miles apart. General Reynolds, with two corps of the Union army was but a few miles away and was hastening to Gettysburg, while Longstreet and Hill were approaching from the west, with Hill's corps several miles in advance.
Buford opened battle against the advance division of Hill's corps under General Heth. Reynolds soon joined and the first day's battle was now in full progress. General Reynolds, while placing his troops in line of battle early in the day, received a death shot in the head by a Confederate sharpshooter. This was a great loss to the Federals, as he was one of the bravest and most able generals in the Union army. No casualty of the war brought more widespread mourning to the North than the death of General John F. Reynolds. But even this calamity did not stay the fury of the battle.
Early in the afternoon the Federals were heavily reënforced, and A. P. Hill had arrived on the field with the balance of his corps, and the roar of battle was unceasing. About the middle of the afternoon a breeze lifted the smoke from the field and revealed that the Federals were falling back towards Gettysburg. They were hard pressed by the Confederates and were pushed back through the town with the loss of many prisoners. The Federals took a position on Cemetery Hill and the first day's battle was over.
If the Confederates had known the disorganized condition of the Federal troops, they might have pursued and captured a large part of the army.
It is thought by many that if "Stonewall" Jackson had lived to be there that at this particular time is where he would have delivered his crushing blow to the Federals and no doubt would have changed the final result of the battle. Meade was still some miles from the field, but on hearing of the death of Reynolds sent General Hancock to take command until he himself should arrive.
The Union loss on the first day was severe. A great commander had fallen and they had suffered the fearful loss of 10,000 men.
Hancock arrived late in the afternoon, after riding at full speed. His presence brought an air of confidence, and his promise of heavy reënforcements all tended to inspire renewed hope in the ranks of the discouraged army.