Battle was now joined in earnest between the two heads of column, and on each side reenforcements were sent forward to take part in this unexpected encounter.  Neither General Lee nor General Meade had expected or desired it.  Both had aimed, in manoeuvring their forces, to select ground suitable for receiving instead of making an attack, and now a blind chance seemed about to bring on a battle upon ground unknown to both commanders.  When the sound of the engagement was first heard by Lee, he was in the rear of his troops at the headquarters which Hill had just vacated, near Cashtown, under the South Mountain.  The firing was naturally supposed by him to indicate an accidental collision with some body of the enemy’s cavalry, and, when intelligence reached him that Hill was engaged with the Federal infantry, the announcement occasioned him the greatest astonishment.  General Meade’s presence so near him was a circumstance completely unknown to Lee, and certainly was not desired by him.  But a small portion of his forces were “up.”  Longstreet had not yet passed the mountain, and the forces of General Ewell, although that officer had promptly fallen back, in obedience to his orders, from the Susquehanna, were not yet in a position to take part in the engagement.  Under these circumstances, if the whole of General Meade’s army had reached Gettysburg, directly in Lee’s front, the advantage in the approaching action must be largely in favor of the Federal army, and a battle might result in a decisive Confederate defeat.

No choice, however, was now left General Lee.  The head of his advancing column had come into collision with the enemy, and it was impossible to retire without a battle.  Lee accordingly ordered Hill’s corps to be closed up, and reenforcements to be sent forward rapidly to the point of action.  He then mounted his horse and rode in the direction of the firing, guided by the sound, and the smoke which rose above the tranquil landscape.

It was a beautiful day and a beautiful season of the year.  The fields were green with grass, or golden with ripening grain, over which passed a gentle breeze, raising waves upon the brilliant surface.  The landscape was broken here and there by woods; in the west rose the blue range of the South Mountain; the sun was shining through showery clouds, and in the east the sky was spanned by a rainbow.  This peaceful scene was now disturbed by the thundering of artillery and the rattle of musketry.  The sky was darkened, here and there, by clouds of smoke rising from barns or dwelling-houses set on fire by shell; and beneath rose red tongues of flame, roaring in response to the guns.