About the time General McDowell arrived on the field at Porter's position, and for an hour or two thereafter, a heavy artillery combat was going on between the Union batteries near Groveton and the Confederate artillery. During this artillery combat, and until 5 o'clock p. m., there was no infantry engagement, except skirmishing and some short and sharp contests between small portions of the opposing forces, and until 6.30 p. m. no musketry was audible to any one in Porter's corps.

On the Confederate side, as it now appears, Porter's display of troops-three brigades in line-in the early part of the afternoon had given rise to the expectation of an attack on their right. This having been reported to General Longstreet, that commander sent his reserve division (Wilcox's) from his extreme left, just north of the Warrenton turnpike, to his extreme right, on the Manassas and Gainesville road. Wilcox reached this latter position about 4 o'clock p. m., and Porter having before that time withdrawn his troops under cover, some troops from the Confederate right (D. R. Jones') were pushed to the front in the woods occupied by Porter's skirmishers, apparently to reconnoiter. This movement gave rise to the impression among Porter's officer's (Morrell's division) that the enemy was about to attack about 5 p. m.

General Pope having arrived some time after noon on the field in the rear of Groveton, and General McDowell's column approaching that part of the field by the Manassas and Sudley road, an attack was ordered upon the enemy's extreme left near Sudley, and a written order was sent, dated 4.30 p. m., to Porter to attack the enemy's right, and, if possible, his rear. After some time had elapsed, General Pope ordered McDowell, with King's division and other troops, to pursue up the Warrenton turnpike the enemy, who, thus to be assailed upon both flanks, would be compelled to retreat.

The attack on Jackson's left was begun by Kearny about 5 p. m.; but the order to Porter was not delivered in time. The messenger did not find General Porter until sunset. Thus at 5 o'clock, nothing having occurred to suggest to General Porter any change in the plan indicated in the joint order to retire behind Bull Run, instead of giving battle that day, the sound of artillery near Sudley, so much apparently to the rear of Groveton, suggested to Porter, who was then at Bethlehem Church, that Sigel was retiring or perhaps being driven back, and that his artillery was then in a new position near the Sudley Springs road.

If it was true that Sigel was being driven back the military situation was extremely perilous, and Porter must instantly do what he could to avert disaster. His order to Morell, which must have been issued at that instant, shows what he proposed to do. It is as follows, viz:

General MORELL:

Push over to the aid of Sigel and strike in his rear. If you reach a road up which King is moving,* and he has got ahead of you, let him pass; but see if you cannot give help to Sigel. If you find him retiring, move back toward Manassas, and, should necessity require it, and you do not hear from me, push to Centreville. If you find the direct road filled, take the one via Union Mills, which is to the right as you return.

F. J. PORTER,

Major-General.

Look to the points of the compass for Manassas.

F. J. PORTER.

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*The Sudley road.

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