When Pope learned of the engagement of Groveton he mistakenly decided
that King had met the head of Jackson’s column in retreat. Confident of
success, he ordered a concentration of his leg weary troops to crush the
Confederate force. Sigel and Reynolds were to attack at dawn, reinforced
by Heintzelman and Reno. McDowell and Porter were ordered to reverse
their course and push toward Gainesville in an effort to cut off
Jackson’s retreat. The text of this order known as the “Joint Order,”
which was received about noon, reads as follows:
[Illustration: THE BATTLE OF SECOND MANASSAS, JULY 21, 1862]
Headquarters Army of Virginia
_Centreville, August_ 29, 1862.
Generals McDowell and Porter:
You will please move forward with your joint commands toward
Gainesville. I sent General Porter written orders to that effect an
hour and a half ago. Heintzelman, Sigel, and Reno are moving on the
Warrenton turnpike, and must now be not far from Gainesville. I desire
that as soon as communication is established between this force and
your own the whole command shall halt. It may be necessary to fall
back behind Bull Run at Centreville to-night. I presume it will be so,
on account of our supplies....
If any considerable advantages are to be gained by departing from this
order it will not be strictly carried out. One thing must be had in
view, that the troops must occupy a position from which they can reach
Bull Run to-night or by morning. The indications are that the whole
force of the enemy is moving in this direction at a pace that will
bring them here by to-morrow night or the next day. My own
headquarters will be for the present with Heintzelman’s corps or at
this place.
Jno. Pope,
_Major-General, Commanding._
Prior to the receipt of the “Joint Order,” Porter had reversed his
course to Centreville and had moved as far as Dawkin’s Branch, located
about 3 miles from Gainesville. Finding the Confederates strongly posted
in his front, he deployed a brigade of his leading division and waited.
McDowell, who arrived shortly thereafter, showed him a dispatch he had
received a few minutes before from Buford, who commanded the Union
cavalry on the right. The dispatch stated that 17 regiments, 1 battery,
and 500 cavalry had passed through Gainesville about 8:45 a. m. This was
the advance of Longstreet’s command which had left Thoroughfare Gap
early that morning and now, followed by heavy reinforcements, was moving
into position on Jackson’s right (Porter’s front).
This information, the generals felt, had not reached Pope. After a
conference, it was decided that in face of this new development they
would take advantage of the latitude the order granted: McDowell would
move towards Groveton, while Porter would remain in the vicinity of his
present position.
The relative quiet in this sector was in sharp contrast to the heavy
fighting now taking place along Jackson’s front. With about 18,000
infantry and 40 guns, Jackson had taken up a position along an
unfinished railroad bed which extended from near Sudley Springs 2 miles
southwesterly to Groveton. The grades and cuts of this road provided
ready-made entrenchments and formed a very strong position. There,
shortly after sunrise, Sigel’s and Reynolds’ columns were seen at a
distance deploying for the attack. About 7 a. m., the Federal batteries
opened fire. By 10:30 a. m., a number of sharp skirmishes had taken
place, but no general assault had been made. About this time Federal
reinforcements of Reno and Kearny reached the field. It was not until 2
p. m., however, that the battle reached its height. All afternoon in
violent but uncoordinated attacks, blue columns gallantly assaulted
Jackson’s line. At one point the Confederate left was pushed back
dangerously near the breaking point, but the gray line steadied and
held. Towards dusk, King’s division, of McDowell’s corps, arrived in
time to take part in the action, engaging a part of Longstreet’s command
which was then advancing on a reconnaissance.
[Illustration: Maj. Gen. Fitz-John Porter, in command of the Fifth Army
Corps at the Second Battle of Manassas. Courtesy Library of Congress.]
Pope, still unaware of the arrival of Longstreet on the field, late in
the day sent Porter the following order to attack Jackson’s right at
once:
Headquarters in the Field,
_August 29_—4:30 p. m.
Major-General Porter:
Your line of march brings you in on the enemy’s right flank. I desire
you to push forward into action at once on the enemy’s flank, and, if
possible, on his rear, keeping your right in communication with
General Reynolds. The enemy is massed in the woods in front of us, but
can be shelled out as soon as you engage their flank. Keep heavy
reserves and use your batteries, keeping well closed to your right all
the time. In case you are obliged to fall back, do so to your right
and rear, so as to keep you in close communication with the right
wing.
John Pope,
_Major-General, Commanding._
This order, dated 4:30 p. m., was received by Porter at Bethlehem Church
about 6:30 p. m. Upon receipt of the order Porter immediately sent his
chief of staff, Locke, to order Morell’s division to attack. Shortly
thereafter Porter rode to the front to find Morell’s preparations for
the attack complete. By this time, however, it was so late that Porter
decided to rescind the order.[1]
During the night the Confederates retired from the advance positions
gained during the day to their original battle line. This fact was
discovered by McDowell and Heintzelman in a reconnaissance on the
evening of the 29th and confirmed by paroled Federal prisoners the
following morning. This led Pope falsely to assume that Lee was in
retreat to Thoroughfare Gap. Immediately plans were initiated to press a
vigorous pursuit. At midnight the following order was issued:
Headquarters, Near Groveton,
_August 30_, 1862—12 M.