Oliver Otis Howard, Autobiography of Oliver Otis Howard, major general , United States army : volume 1

That day, March 10th, Sumner gave his men, unaccustomed to marching, a hard trial of seventeen miles. “What's seventeen miles,” he asked at evening, “for a soldier?” It had rained-poured-most of the time. I had commanded my brigade and also the advance guard. The mud was first slippery and then deep; the weather was chilly and damp, making the rests uncomfortable and the night worse, as we were without canvas shelter, yet owing to previous discipline there was none of the Bull Run straggling. Sumner's division, made up of the three brigades, and the Eighth Illinoiso Cavalry, with Clarke's and Frank's six-gun batteries of artillery, continued its march the 11th, and kept on to Manassas Junction and beyond. The Confederate cavalry leader, J. E. B. Stuart, watched our advancing forces, retiring from knoll to knoll, from grove to grove, as we pressed on. That cavalry was Johnston's rear guard, when his army was in motion southward, and became his outpost and picketing force as soon as Johnston halted. Sumner stopped his general movement at Warrenton Junction, thirteen miles south of Manassas. Now he had two divisions, because Blenker's, made up mostly of Germans, had joined him at Manassas.

In spite of McClellan's objection, Mr. Lincoln had caused him to organize his Potomac force into army corps. McClellan complied on March 13th, so that Sumner, during his first march, came into command of the Second Corps. I. B. Richardson was appointed commander of our division, John Sedgwick and Louis Blenker of the other two. The actual change of commanders was effected while we were tramping the Virginia mud, and by small fires drying sundry spots large enough to sleep on.