I was to be assigned to the command of the Cavalry Corps of the Army of the Potomac.

The information staggered me at first, for I knew well the great responsibilities of such a position; moreover, I was but slightly acquainted with military operations in Virginia, and then, too, the higher officers of the Army of the Potomac were little known to me, so at the moment I felt loth to undergo the trials of the new position.

Indeed, I knew not a soul in Washington except General Grant and General Halleck, and them but slightly, and no one in General Meade's army, from the commanding general down, except a few officers in the lower grades, hardly any of whom I had seen since graduating at the Military Academy.
Thus it is not much to be wondered at that General Thomas's communication momentarily upset me.

But there was no help for it, so after reflecting on the matter a little I concluded to make the best of the situation.

As in Virginia I should be operating in a field with which I was wholly unfamiliar, and among so many who were strangers, it seemed to me that it would be advisable to have, as a chief staff-officer, one who had had service in the East, if an available man could be found.