There had been great consternation in Petersburg, as we were well aware, about a rumored mine that we were going to explode.  They knew we were mining, and they had failed to cut our mine off by countermining, though Beauregard had taken the precaution to run up a line of intrenchments to the rear of that part of their line fronting where they could see that our men were at work.  We had learned through deserters who had come in that the people had very wild rumors about what was going on on our side.  They said that we had undermined the whole of Petersburg; that they were resting upon a slumbering volcano and did not know at what moment they might expect an eruption.  I somewhat based my calculations upon this state of feeling, and expected that when the mine was exploded the troops to the right and left would flee in all directions, and that our troops, if they moved promptly, could get in and strengthen themselves before the enemy had come to a realization of the true situation.  It was just as I expected it would be.  We could see the men running without any apparent object except to get away.  It was half an hour before musketry firing, to amount to anything, was opened upon our men in the crater.  It was an hour before the enemy got artillery up to play upon them; and it was nine o’clock before Lee got up reinforcements from his right to join in expelling our troops.

The effort was a stupendous failure.  It cost us about four thousand men, mostly, however, captured; and all due to inefficiency on the part of the corps commander and the incompetency of the division commander who was sent to lead the assault.

After being fully assured of the failure of the mine, and finding that most of that part of Lee’s army which had been drawn north of the James River were still there, I gave Meade directions to send a corps of infantry and the cavalry next morning, before Lee could get his forces back, to destroy fifteen or twenty miles of the Weldon Railroad.  But misfortunes never come singly.  I learned during that same afternoon that Wright’s pursuit of Early was feeble because of the constant and contrary orders he had been receiving from Washington, while I was cut off from immediate communication by reason of our cable across Chesapeake Bay being broken.  Early, however, was not aware of the fact that Wright was not pursuing until he had reached Strasburg.  Finding that he was not pursued he turned back to Winchester, where Crook was stationed with a small force, and drove him out.  He then pushed north until he had reached the Potomac, then he sent McCausland across to Chambersburg, Pa., to destroy that town.  Chambersburg was a purely defenceless town with no garrison whatever, and no fortifications; yet McCausland, under Early’s orders, burned the place and left about three hundred families houseless.  This occurred on the 30th of July.  I rescinded my orders for the troops to go out to destroy the Weldon Railroad, and directed them to embark for Washington City.  After burning Chambersburg McCausland retreated, pursued by our cavalry, towards Cumberland.  They were met and defeated by General Kelley and driven into Virginia.