June 25, 1864 – A Federal colonel proposed opening a gap in the Confederate siege lines by digging a tunnel under them and detonating explosives.
Major General Ambrose E. Burnside’s IX Corps of the Army of the Potomac held the center of the Federal siege line outside Petersburg. In their front, about 150 yards away, troops of General Robert E. Lee’s Confederate Army of Northern Virginia held a strong redoubt on high ground called Elliott’s Salient. A soldier of the 48th Pennsylvania (a regiment of anthracite coal miners from Schuylkill County) remarked, “We could blow that damn fort out of existence if we could run a mine shaft under it.”
The 48th’s commander, Lieutenant Colonel Henry Pleasants, himself a mining engineer, overheard the soldier and developed a plan that he submitted to his superior, Brigadier General Robert B. Potter. In later congressional testimony, Potter said:
“About the 24th of June, the idea of mining under the enemy’s works in my immediate front was suggested to me; in fact, I had thought of it before, and several others had thought the same thing… Pleasants… came to my quarters and suggested to me that he was familiar with mining, and that many of the men in his regiment were miners, and that they thought they could undermine one of the enemy’s works in my immediate front. After some conversation with him, I wrote a communication to General Burnside… suggesting this plan of mining the enemy’s works, and giving some of the details.”
Potter wrote Burnside that Pleasants–
“–is of the opinion that they could run a mine forward at the rate of from 25 to 50 feet per day, including supports, ventilation, and so on. It would be a double mine, for as we cannot ventilate by shafts from the top, we would have to run parallel tunnels, and connect them every short distance by lateral ones, to secure a circulation of air, absolutely essential here, as these soils are full of mephitic vapors.”
Burnside summoned Potter and Pleasants to his headquarters on the night of the 24th. Pleasants later testified that he “explained to him carefully the mode of ventilating the mine and everything about it. He seemed very much pleased with the proposition, and told me to go right on with the work.”
Burnside then sought approval from Major General George G. Meade, commanding the Army of the Potomac, and Lieutenant General Ulysses S. Grant, commanding all Federal armies. According to Meade:
“I sanctioned its prosecution, though at the time, from the reports of the engineers and my own examination, I was satisfied the location of the mine was such that its explosion would not be likely to be followed by any important result, as the battery to be destroyed was in a re-entering part of the enemy’s line, exposed to an enfilading fire, and reverse fire from points both on the right and left.”
Grant later wrote in his memoirs that he approved it only “as a means of keeping the men occupied.” Many Federal engineers called the project “claptrap and nonsense” because ventilation limitations prevented shafts from being longer than 400 feet. However, Pleasants devised an innovative and undetectable ventilating system for this shaft, which would eventually stretch 511 feet.
Digging started on the 25th, with the men using makeshift tools; a civilian’s theodolite enabled Pleasants to survey for direction and distance. As he testified, “My regiment was only about 400 strong. At first I employed but a few men at a time, but the number was increased as the work progressed, until at last I had to use the whole regiment, non-commissioned officers and all.”
A soldier of the nearby 13th Ohio watched the Pennsylvanians and later wrote:
“The dirt was carried out in cracker boxes and jute bags which had contained grain for the commissary department. The men working in the mine had only shirt and drawers on, and some were minus shirt even. I used to watch them popping in and out of the hole like so many brown gophers.”
The tunneling originated in a steep embankment behind the Federal picket line, out of Confederate view. Even so, on the last day of June, Confederate Brigadier General E. Porter Alexander, wounded by a sharpshooter, warned before taking leave that Federals were tunneling under Elliott’s Salient. But Confederate engineers, like their Federal counterparts, did not believe that men could dig a tunnel long enough to reach their lines. The work continued into July.
CivilWarDailyGazette.com; Davis, William C., Death in the Trenches: Grant at Petersburg (Alexandria, VA: Time-Life Books, 1983), p. 67-68; Foote, Shelby, The Civil War: A Narrative: Volume 3: Red River to Appomattox (Vintage Civil War Library, Knopf Doubleday Publishing Group, Kindle Edition, 2011), Loc 9305-15, 11144-54; Fredriksen, John C., Civil War Almanac (New York: Checkmark Books, 2007), p. 461; Linedecker, Clifford L (ed.), The Civil War A to Z (Ballantine Books, 2002), p. 76; Long, E.B. with Long, Barbara, The Civil War Day by Day (New York: Da Capo Press, Inc., 1971), p. 528; McPherson, James M., Battle Cry of Freedom: The Civil War Era (Oxford History of the United States Book 6, Oxford University Press, Kindle Edition, 1988), p. 758; Wert, Jeffry D., Historical Times Illustrated Encyclopedia of the Civil War (New York: Harper & Row, 1986, Patricia L. Faust ed.), p. 190