Editing Battle of the Crater (section)

==Background==
{{more citations needed section|date=July 2017}}
During the Civil War, [[Petersburg, Virginia]], was an important railhead, where four railroad lines from the south met before they continued to [[Richmond, Virginia]], the capital of the Confederacy. Most supplies to General Lee's army and Richmond funneled through that location. Consequently, the Union regarded it as the "back door" to Richmond and as necessary for its defense.<ref>Eicher, p. 687.</ref> The result was the [[siege of Petersburg]]. It was actually trench warfare, rather than a true [[siege]], as the armies were aligned along a series of fortified positions and trenches more than {{convert|20|mi|km}} long, extending from the old [[Battle of Cold Harbor|Cold Harbor]] battlefield near Richmond to areas south of Petersburg.

After Lee stopped Grant's attempt to seize [[Second Battle of Petersburg|Petersburg on June 15]], the battle settled into a stalemate. Grant had learned a hard lesson at Cold Harbor about attacking Lee in a fortified position and was chafing at the inactivity to which Lee's trenches and forts had confined him. Finally, [[Lieutenant Colonel (United States)|Lt. Col.]] [[Henry Pleasants]], commanding the [[48th Pennsylvania Volunteer Infantry Regiment|48th Pennsylvania Infantry]] of Major General [[Ambrose E. Burnside]]'s [[IX Corps (Union Army)|IX Corps]], offered a novel proposal to break the impasse.

Pleasants, a mining engineer from [[Pennsylvania]] in civilian life, proposed digging a long mine shaft under the [[Confederate States Army|Confederate Army]] lines and planting explosive charges directly underneath a fort (Elliott's Salient) in the middle of the Confederate First Corps line. If successful, not only would all the defenders in the area be killed, but also a hole in the Confederate defenses would be opened. If enough [[Union Army|Union]] troops filled the breach quickly enough and drove into the Confederate rear area, the Confederates would not be able to muster enough force to drive them out, and Petersburg might fall. Burnside, whose reputation had suffered from his 1862 defeat at the [[Battle of Fredericksburg]] and his poor performance earlier that year at the [[Battle of Spotsylvania Court House]], agreed to Pleasants's plan.

===Mine construction===
[[File:Petersburg crater sketch LOC.jpg|thumb|Contemporary sketch of Col. Pleasants supervising the placement of powder in the mine]]
[[File:NPS marker deicting details of the mine.jpg|thumb|National Park Service marker depicting details of the mine]]
Digging began in late June, but even Grant and Meade saw the operation as a "mere way to keep the men occupied" and doubted it of any actual tactical value. They quickly lost interest, and Pleasants soon found himself with few materials for his project, and his men even had to forage for wood to support the structure.

Work progressed steadily, however. Earth was removed by hand and packed into improvised sledges made from cracker boxes fitted with handles, and the floor, wall, and ceiling of the mine were shored up with timbers from an abandoned wood mill and even from tearing down an old bridge.

The shaft was elevated as it moved toward the Confederate lines to make sure moisture did not clog up the mine, and fresh air was drawn in by an ingenious air-exchange mechanism near the entrance. A canvas partition isolated the miners' air supply from outside air and allowed miners to enter and exit the work area easily. The miners had constructed a vertical exhaust shaft located well behind Union lines. At the vertical shaft's base, a fire was kept continuously burning. A wooden duct ran the entire length of the tunnel and protruded into the outside air. The fire heated stale air inside of the tunnel, drawing it up the exhaust shaft and out of the mine by the [[stack effect|chimney effect]]. The resulting vacuum then sucked fresh air in from the mine entrance via the wooden duct, which carried it down the length of the tunnel to the place in which the miners were working.<ref>Corrigan, pp. 36–37.</ref> That avoided the need for additional ventilation shafts, which could have been observed by the enemy, and it also easily disguised the diggers' progress.

On July 17, the main shaft reached under the Confederate position. Rumors of a mine construction soon reached the Confederates, but Lee refused to believe or act upon them for two weeks before he commenced countermining attempts, which were sluggish and uncoordinated, and were unable to discover the mine. However, General [[John Pegram (general)|John Pegram]], whose batteries would be above the explosion, took the threat seriously enough to build a new line of trenches and artillery points behind his position as a precaution.<ref name=blake53>{{harvnb|Blake|1935|pp=53–54}}</ref> Shafts were also sunk by the Confederates in an effort to intercept the passage.<ref>{{harvnb|Chernow|2017|p=427}}</ref> Pleasants became aware of the Confederate's counter-movements and was able to frustrate their effort by changing the direction of the main and lateral galleries while increasing their depth below the surface.<ref>{{harvnb|Blake|1935|p=54}}</ref>

The mine was in a "T"-shape. The approach shaft was {{convert|511|ft|m}} long, starting in a sunken area downhill and more than {{convert|50|ft|m}} below the Confederate battery, making detection difficult. The tunnel entrance was narrow, about {{convert|3|ft|m|0}} wide and {{convert|4.5|ft|m}} high. At its end, a perpendicular gallery of {{convert|75|ft|m}} extended in both directions. Grant and Meade suddenly decided to use the mine three days after it was completed after a failed attack known later as the [[First Battle of Deep Bottom]]. Union soldiers filled the mine with 320 kegs of gunpowder, totaling {{convert|8,000|lb|kg}}. The explosives were approximately {{convert|20|ft|m|sigfig=1}} under the Confederate works, and the T-gap was packed shut with {{convert|11|ft|m|0}} of earth in the side galleries. A further {{convert|32|ft|m|0}} of packed earth was placed in the main gallery to prevent the explosion blasting out the mouth of the mine. On July 28, the powder charges were armed.<ref name=chernow426>{{harvnb|Chernow|2017|pp=426–29}}</ref><ref name=blake53/>

===Preparation===
Burnside had trained a division of [[United States Colored Troops]] (USCT) under Brigadier General [[Edward Ferrero]] to lead the assault. The division consisted of two brigades, one designated to go to the left of the crater and the other to the right. A regiment from both brigades was to leave the attack column and extend the breach by rushing perpendicular to the crater, and the remaining regiments were to rush through, seizing the Jerusalem Plank Road just {{convert|1600|ft|m}} beyond, followed by the churchyard and, if possible, Petersburg itself. Burnside's two other divisions, made up of white troops, would then move in, supporting Ferrero's flanks and race for Petersburg itself. Two miles (3&nbsp;km) behind the front lines, out of sight of the Confederates, the men of the USCT division were trained for two weeks on the plan.<ref>Trudeau, p. 110.</ref>

Despite the careful planning and intensive training, on the day before the attack, Meade, who lacked confidence in the operation, ordered Burnside not to use the black troops in the lead assault. He claimed that if the attack failed, black soldiers would be killed needlessly, creating political repercussions in the North. Meade may have also ordered the change of plans because he lacked confidence in the black soldiers' abilities in combat and feared that if they were butchered, Radical Republicans would make an issue out of it and claim they were deliberately allowed to be killed.<ref>McPherson, p. 759.</ref> Burnside protested to Grant, who sided with Meade. When volunteers were not forthcoming, Burnside selected a replacement white division by having the three commanders draw lots. Brigadier General [[James H. Ledlie]]'s 1st Division was selected, but he failed to brief the men on what was expected of them and was reported during the battle to be drunk, well behind the lines, and not providing leadership. Ledlie would be dismissed for his actions during the battle. Ledlie, a civilian soldier with no proper military training, also commanded the smallest and weakest division in the army; one brigade was made of heavy artillery regiments that had not performed well in combat so far and Burnside himself had complained about their performance during the June 18 assaults on Petersburg. Worse than that, Ledlie was known as a coward; during the battle on June 18 he had hidden behind the lines and although his officers and enlisted men knew it, this escaped Burnside's notice.<ref name=chernow426/>