Horace Greeley, The American Conflict: A History of the Great Rebellion in the United States of America, 1860-65: its Causes, Incidents, and Results: Intended to exhibit especially its moral and political phases with the drift and progress of American opinion respecting human slavery from 1776 to the close of the War for the Union. Volume II.

[179] Sulphur Springs, and Waterloo Bridge, kept moving heavy columns up their side of the river, with evident intent to flank and fall upon our right; and Pope, facing along the turnpike from Warrenton to Gainesville, resolved there to give battle. Meantime, Heintzelman's long-expected corps from McClellan's army had reached Warrenton Junction,¹ and Porter had reported from the neighborhood of Bealton Station; while Sturgis, Cox, and Franklin, were telegraphed from Washington to be just at hand. Pope, therefore, believed, and had a right to believe, that he was to be supported, in the struggle now imminent, by 40,000 to 50,000 veterans from the Army of the Potomac, and had made dispositions and given orders accordingly. He requested Gen. Halleck to push Franklin with all speed to Gainesville; and sent orders to Manassas Junction that the first division which reached that point from Alexandria should halt and take post in the works at that place, pushing forward its cavalry toward Thoroughfare Gap to watch the enemy's movements in that quarter; while Gen. Sturgis, commanding at Alexandria, had already been directed² by him to post strong guards along the railroad from Manassas Junction to Catlett's, personally superintending the execution of this order.

Sigel, who had slowly moved up the Rappahannock, and encountered³ a Rebel force at Great Run, two miles below the Sulphur Springs, had easily driven it, but not till it had had time to destroy certain bridges; and the great flood then prevailing compelled him to halt and rebuild them before advancing. Supported by Gens. Reno and Banks, he crossed Great Run next morning⁴ and occupied Sulphur Springs under a heavy fire of artillery from the Rebel batteries over the Rappahannock, rebuilding the Sulphur Springs bridge, and pushing forward in the direction of Waterloo Bridge, which was occupied by Gen. Buford's cavalry at noon of that day; Sigel's advance, under Milroy, arriving late in the afternoon: when our army may be said to have been concentrated, facing to the west, with Sigel's corps and Buford's cavalry near the Rappahannock at Waterloo Bridge, with Banks's behind it; Reno's farther east, and very near Sulphur Springs; McDowell, with Ricketts's and King's divisions, at Warrenton; Heintzelman behind him at Warrenton Junction, where Sturgis and Cox were hourly looked for; while Franklin was expected to come in on his right, and Porter to push forward and join Reno. But unsuccessful fighting and constant marching had by this time reduced Sigel's corps to 9,000 effectives; Banks's to 5,000; McDowell's, including Reynolds's division, to 15,500; and Reno's to 7,000; to which add 4,000 thoroughly used — up cavalry, and Pope's army proper could bring into action hardly 40,000 men. Add to these the corps of Heintzelman and Porter, just arrived from McClellan's army, and it might be said that his whole command numbered nearly 60,000; but Heintzelman had reached Warrenton Junction by railroad, without artillery or wagons, with only four rounds of ammunition to the man, and without horses even for his field