ched an aide to General Porter with orders to join
Hooker at once. The aide was instructed to inform General Porter of the
immediate necessity of moving at once, and to remain and guide him to
the place. But Porter utterly refused to obey the order. Most
fortunately for our army, Jackson, ignorant of Hooker's weakness,
determined to retreat by way of Centreville; a mistake which prevented
most serious consequences to us. Jackson in his retreat was hotly
pursued, and on the 28th a severe battle took place between McDowell's
corps and the retreating column, in which our forces gained decided
advantages. On the 29th, Jackson was again near the old Bull Run
battle-ground, and a terrific battle ensued, which lasted with great
fury from daylight until dark. The rebels were driven from the field,
which was occupied by our men. General Pope sent peremptory orders to
Fitz John Porter to move at once upon Centreville; which would have cut
off Jackson's retreat; but again this commander refused to obey orders,
and Jackson was enabled to unite with Lee, who had by this time reached
Thoroughfare Gap, and was pushing on toward him. Had the orders of
General Pope been carried out, Jackson must without doubt have been
crushed before Lee's forces could by any possibility have reached the
field of action.

On the following day the whole of both armies were brought face to face
with each other. General Pope, by this time hopeless of any aid from the
fresh troops he had expected long before this from Washington, and aware
of the disaffection of the largest and freshest corps in his command,
although nearly discouraged, determined to give battle and inflict as
much damage as possible upon the enemy. His force now, including
Porter's corps, was about forty thousand. The whole of Lee's and
Jackson's forces now pressed upon our lines with terrible effect.

The action raged with great fury for several hours; the rebels
constantly massing heavy columns against our lines, especially upon the
left, where McDowell's and Sigel's corps resisted the onset with great
bravery, but were at length forced to yield, when an utter rout took
place; the whole army falling back upon Centreville in great disorder.
On this day, for the first time in all these long series of battles,
Porter's corps was brought into action. The conduct of the corps, in the
early part of the day, showed a determination on the part of its leaders
not to fight, and the men fell back