It was General Stevens’s last letter.
While the beaten and distracted Union commander was trying to straighten out his forces huddled about Centreville, uncertain whether to risk further conflict or to fall back to the defenses of Washington, Lee was moving his whole army in one column, to fall upon his enemy’s line of retreat and rear. The very day after the battle he advanced Jackson’s wing across Bull Run by Sudley Ford to the Little River turnpike, which runs straight to Fairfax Court House, and there intersects the Alexandria and Warrenton pike, eight miles behind Centreville. On this Monday morning Jackson was marching down the turnpike with Longstreet and his whole wing following closely in support, thus turning the Union army at Centreville, and moving to fall upon its only line of retreat; “to strike it under the ribs,” as General Stevens so clearly foresaw. Pope had taken no steps to anticipate or guard against this fatal flank movement. He was groping in the dark, utterly at a loss what course to pursue, and consequently he did nothing until noon, when startling news forced him to decision and to action.
Jackson’s Flank March to turn Centreville.
Such was the situation,—the bulk of the Union forces grouped about Centreville with their distraught commander, the victorious rebel army, in one strong column, Jackson at its head, turning their flank and striking far in their rear,—when, at one P.M., two cavalrymen dashed up to General Stevens’s headquarters. They bore orders to him from General Pope to march immediately across country, guided by the two troopers, to the Little River pike, and there take position and hold in check a column of the enemy reported advancing down that road.
General Stevens soon had his division under arms, moved across the fields, and entered the Alexandria pike a short distance east of Centreville. Here Ferrero’s brigade of Reno’s division, the other brigade after its heavy loss on the 29th not being again called upon, fell in behind and followed. The scanty column moved down the road a mile and a half, then turned off to the left, and followed a farm road in a northeasterly direction between the two pikes. As General Stevens and staff were riding at the head of the column the cavalrymen told how they had been out foraging that morning to the Little River pike, and had run into a heavy column of the enemy advancing down it, and had made all haste to gallop to Pope’s headquarters with the news. Thence they were at once dispatched to General Stevens with the orders already related, and directed to guide his column to the endangered road.
This startling news brought him about noon by these cavalrymen was unquestionably the first intelligence that Pope received of Lee’s thrust. His own orders prove this, for he not only immediately dispatched General Stevens to seize and hold the Little River pike, but detached Hooker from his division and sent him to Germantown, a point just in front of Fairfax Court House, where the two pikes meet, to take charge of some troops there and post them to resist the threatening movement, ordered McDowell—
“immediately to march rapidly back to Fairfax Court House with your whole division (corps) and assume command of the two brigades there, and occupy Germantown with your whole force, so as to cover the turnpike from this place to Alexandria. Jackson is reported advancing on Fairfax with 20,000 men,”—
and soon afterwards hurried Heintzelman’s two divisions down the pike toward Fairfax. And it was while thus moving that General Kearny received General Stevens’s urgent summons, and opportunely hastened to the stricken field, as will soon be related.