General Patterson had crossed the Potomac early in July, with a force of thirty thousand men, and was encamped at Martinsburgh, on the 12th, having instructions from the Commander-in-chief to hold the rebel army under General Johnston in check, should he attempt to move forward to Manassas for the purpose of reinforcing Beauregard’s command at that point. Johnston was at Winchester, on the direct route to Manassas Gap, twenty-five miles from Martinsburgh, and it was a matter of vital importance that he should be prevented from making a further advance. The entire marching force of General McDowell was but about fifty-five thousand, while twenty thousand were left as a reserve at Washington and vicinity, under the command of General Mansfield. And thus the combatants stood, when a day of fearful, bloody ending dawned upon them—a day almost without a parallel in the world’s history for deeds of daring and stubborn endurance, unflinching bravery, and wild panic. Manassas was selected by the Confederates on account of its controlling position. Nature had done very much towards rendering it a second Gibraltar, and art had completed the work. The country around was wild and broken, with but few roads fit for the movements of an army, and those easily guarded. Centreville was twenty-two miles distant from Washington, and Manassas Junction six or seven more. About midway between the two flowed the little rivulet of Bull Run, in a general direction from north-west to south-east. A road led from Centreville to the Junction, crossing the Run three miles from that place, at “Blackburn’s Ford,” while a turnpike running towards Warrenton, also crossed Bull Run at Stone Bridge, four miles distant. Somewhat east of south, a country road from Centreville crossed Bull Run, and the railroad at “Union Mills.” The Confederate force was distributed along the Run from Union Mills to the Stone Bridge, with reserves and a strongly fortified position near the junction. The array of General McDowell, when it marched to attack that position, numbered about 30,000 men, consisting, with the exception of 700 or 800 regular troops, of raw volunteers, none of whom had been under military discipline more than two or three months. Added to this must be remembered the fact that, within three days, ten thousand of the number would have a right to claim their dismissal, as their term of enlistment (three months) would then expire. An army, consequently, less prepared to march to the attack of a strongly fortified position it would have been difficult to assemble; and this was rendered more fatal in its effects from the fact that the officers, with the exception of a few who had fought in the Mexican war, were unused to actual fighting, and almost totally unacquainted with their different commands.