Petersburg National Military Park, Virginia

by Richard Wayne Lykes

At several places east of the city the opposing lines were extremely close together. One of these locations was in front of Elliott’s Salient, a Confederate strong point near Cemetery Hill and old Blandford Church. Here the Confederate position and the Union picket line were less than 400 feet apart. Because of the proximity of the Union line, Elliott’s Salient was well fortified. Behind earthen embankments was a battery of four guns, and two veteran South Carolina infantry regiments were stationed on either side. Behind these were other defensive works; before them the ground sloped gently downward toward the Union advance line.

Cross-section view of a scale model of the Union tunnel.

THE FEDERAL TUNNEL Built by the Forty-eighth Pennsylvania Regiment, commanded by Colonel Henry Pleasants. THE EXPLOSION OF THIS MINE PRODUCED THE CRATER FEDERAL LINE ESTABLISHED JUNE 18, 1864 TUNNEL STARTED JUNE 25, 1864 TUNNEL SLOPED UP TO AVOID HEAVY CLAY 8000 LBS POWDER PLACED HERE JULY 27, 1864 CONFEDERATE PEGRAMS BATTERY DESTROYED BY EXPLOSION JULY 30, 1864

The explosion of the Union mine as recorded by A. R. Waud, a contemporary artist. From Battles and Leaders of the Civil War.

This forward Union line was built on the crest of a ravine which had been crossed on June 18. Through this ravine, and between the sentry line and the main line, lay the roadbed of the Norfolk and Petersburg Railroad. The front in this sector was manned by Gen. Ambrose E. Burnside’s IX Corps. Among the many units which composed this corps was the 48th Regiment, Pennsylvania Veteran Volunteer Infantry. A large proportion of this regiment had been coal miners, and it seemed to have occurred to one or more of them that Elliott’s Salient would provide an excellent place to use their civilian occupation. Lt. Col. Henry Pleasants, the commanding officer of the 48th and a mining engineer by profession, overheard one of the enlisted men mutter, “We could blow that damned fort out of existence if we could run a mine shaft under it.” From this and similar remarks came the germ of the idea for the Union mine. This is what the 48th Regiment proposed to do: dig a long gallery from the bottom of the ravine behind their picket line to a point beneath the Confederate battery at Elliott’s Salient, blow up the position by means of powder placed in the end of the tunnel, and, finally, send a strong body of troops through the gap created in the enemy’s line by the explosion. They saw as the reward for their effort the capitulation of Petersburg and, perhaps, the end of the war.

After obtaining the permission of Burnside and Grant, Pleasants and his men commenced digging their mine shaft on June 25. The lack of proper equipment made it necessary constantly to improvise tools and apparatus with which to excavate. Mining picks were created from straightened army picks. Cracker boxes were converted into hand-barrows in which the dirt was removed from the end of the tunnel. A sawmill changed a bridge into timber necessary for shoring up the mine. Pleasants estimated both direction and depth of the tunnel by means of a theodolite (old-fashioned even in 1864) sent him from Washington. The outmoded instrument served its purpose well, however; the mine shaft hit exactly beneath the salient at which it was aimed.

One of the most remarkable features of the gallery was the method devised to supply the diggers at the end with fresh air. The longer the tunnel grew, the more serious became the problem of ventilation. It had been considered impossible to dig a tunnel for any considerable distance without spacing shafts at regular intervals in order to replace the polluted air with a fresh supply. This problem had been solved by the application of the simple physical principle that warm air tends to rise. Behind the Union picket line and to the right of the mine gallery, although connected with it, the miners dug a ventilating chimney. Between the chimney and the mine entrance they erected an airtight canvas door. Through that door and along the floor of the gallery there was laid a square wooden pipe. A fire was then built at the bottom of the ventilating shaft. As the fire warmed the air it went up the chimney. The draft thus created drew the bad air from the end of the tunnel where the men were digging. As this went out, fresh air was drawn in through the wooden pipe to replace it.

Work on the tunnel had been continuously pushed from the start on June 25. By July 17 the diggers were nearly 511 feet from the entrance and directly beneath the battery in Elliott’s Salient. The Confederates had become suspicious by this time, for the faint sounds of digging could be heard issuing from the earth. Their apprehension took the form of countermines behind their own lines. Several of these were dug in an effort to locate the Union gallery. Two were very close, being sunk on either side of where the Pennsylvanians were at work. Although digging in the countermines continued throughout the month of July, Confederate fears seemed to quiet down during the same period. There were many reasons for this. One was the failure of their tunnels to strike any Union construction. Another major reason, undoubtedly, was a belief held by many that it was impossible to ventilate a shaft of any length over 400 feet without constructing air shafts along it.