Battle of the Crater The Battle of the Crater was a battle of the American Civil War , part of the Siege of Petersburg . It took place on July 30 , 1864 , between the Confederate Army of Northern Virginia , commanded by General Robert E . Lee and the Union Army of the Potomac , commanded by Major General Ambrose Burnside ( under the direct supervision of the general - in - chief , Lt . Gen . Ulysses S . Grant ) . After weeks of preparation , on July 30 the Federals exploded a mine in Maj . Gen . Ambrose E . Burnside ' s IX Corps sector , blowing a gap in the Confederate defenses of Petersburg , Virginia . From this propitious beginning , everything deteriorated rapidly for the Union attackers . Unit after unit charged into and around the crater , where soldiers milled in confusion . Grant considered the assault " the saddest affair I have witnessed in the war . " The Confederates quickly recovered and launched several counterattacks led by Brig . Gen . William Mahone . The breach was sealed off , and the Federals were repulsed with severe casualties . Brig . Gen . Edward Ferrero ' s division of black soldiers was badly mauled . This may have been Grant ' s best chance to end the Siege of Petersburg . Instead , the soldiers settled in for another eight months of trench warfare . Burnside was relieved of command for the last time for his role in the debacle , and he was never again returned to command . Background . During the Civil War , Petersburg , Virginia , was an important railhead , where four railroad lines from the south met before continuing to Richmond , Virginia , the capital of the Confederacy . Most of the supplies to Lee ' s army and to the city of Richmond funneled through this point . Consequently , the Union regarded it as the " back door " to Richmond , without which defending the Confederate capital would be impossible . The result was the Siege of Petersburg ( which was actually trench warfare rather than a true siege ) , in which the armies were aligned along a series of fortified positions and trenches more than long , extending from the old Cold Harbor battlefield near Richmond to areas south of Petersburg . After Lee held at bay Grant ' s attempt to seize 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 , Lt . Col . Henry Pleasants , commanding the 48th Pennsylvania Infantry of Maj . Gen . Ambrose E . Burnside ' s 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 underneath the Confederate lines and planting explosive charges directly underneath a fort ( Elliott ' s Salient ) in the middle of the Confederate First Corps line . If successful , this would not only kill all the defenders in the area , it would also open a hole in the Confederate defenses . If enough 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 , gave Pleasants the go - ahead . Mine construction . Digging began in late June , but even Grant and Major General George Meade saw the operation as , " A mere way to keep the men occupied , " and doubted it of any actual strategic value . They quickly lost interest and Pleasants soon found himself with few materials for his project , to the extent that his men 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 pumped in via an ingenious air - exchange mechanism near the entrance . The miners had constructed a ventilation shaft located well behind Union lines , and connected it to the mine with canvas , which isolated the mine from outside air . At the shaft ' s base , a fire was kept continuously burning . Meanwhile , 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 , forcing it up the ventilation shaft and out of the mine . 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 location where the miners were working . This precluded the need for additional ventilation shafts that could have been observed by the enemy , and served well in disguising 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 it for two weeks before commencing countermining attempts , which were sluggish and uncoordinated , and were unable to discover the mine . General John Pegram , whose batteries would be above the explosion , did , however , take the threat seriously enough to build a new line of trenches and artillery points behind his position as a precaution . The mine was in a " T " shape . The approach shaft was long , starting in a sunken area downhill and more than below the Confederate battery , making detection difficult . The tunnel entrance was narrow , about wide and high . At its end , a perpendicular gallery of extended in both directions . Grant and Meade suddenly decided to use the mine three days after it was complete after a failed attack known later as the First Battle of Deep Bottom . The Federals filled the mine with 320 kegs of gunpowder , totaling . The explosives were approximately underneath the Confederate works and the T gap was packed shut with of earth in the side galleries and a further of packed earth in the main gallery to prevent the explosion blasting out the mouth of the mine . On July 28 , the powder charges were armed . Preparation . Burnside had trained a division of United States Colored Troops ( USCT ) under Brig . Gen . 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 each brigade was to leave the attack column and extend the breach by rushing perpendicular to the crater , while the remaining regiments were to rush through , seizing the Jerusalem Plank Road just 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 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 . Despite this careful planning and intensive training ( by Civil War standards ) , the day before the attack , Meade , who lacked confidence in the operation , ordered Burnside not to use the black troops in the lead assault , claiming 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 black soldiers ' abilities in combat . Burnside protested to General Grant , who sided with Meade . When volunteers were not forthcoming Burnside selected a replacement white division by having the three commanders draw lots . Brig . Gen . 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 providing no leadership . ( Ledlie would be dismissed for his actions during the battle . ) Battle . The plan called for the mine to be detonated between 3 : 30 and 3 : 45am on the morning of July 30 . Pleasants lit the fuse accordingly , but as with the rest of the mine ' s provisions , they had been given poor quality fuse , which his men had had to splice themselves . After more and more time passed and no explosion occurred ( the impending dawn creating a threat to the men at the staging points , who were in view of the Confederate lines ) , two volunteers from the 48th Regiment ( Lt . Jacob Douty and Sgt . Harry Reese ) crawled into the tunnel . After discovering the fuse had burned out at a splice , they spliced on a length of new fuse and relit it . Finally , at 4 : 44 a . m . , the charges exploded in a massive shower of earth , men , and guns . A crater ( still visible today ) was created , long , wide , and at least deep . The explosion immediately killed 278 Confederate soldiers , and stunned Confederate troops did not direct any significant musket or artillery fire at the enemy for at least 15 minutes . However , Ledlie ' s untrained division was not prepared for the explosion , and reports indicate they waited ten minutes before leaving their own entrenchments . Footbridges were supposed to have been placed to allow them to quickly cross their own trenches , but these were missing , meaning the men had to climb in and out of their own trenches just to reach no - man ' s land . Once they had wandered to the crater , instead of moving around it as the black troops had been trained to do , they thought it would make an excellent rifle pit and it would be well to take cover . Therefore , they moved down into the crater itself , wasting valuable time while the Confederates , under Brig . Gen . William Mahone , gathered as many troops together as they could for a counterattack . In about an hour ' s time , they had formed up around the crater and began firing rifles and artillery down into it , in what Mahone later described as a " turkey shoot " . The plan had failed , but Burnside , instead of cutting his losses , sent in Ferrero ' s men . Now faced with considerable flanking fire , they also went down into the crater , and for the next few hours , Mahone ' s soldiers , along with those of Maj . Gen . Bushrod Johnson and artillery , slaughtered the IX Corps as it attempted to escape from the crater . Some Union troops eventually advanced and flanked to the right beyond the Crater to the earthworks and assaulted the Confederate lines , driving the Confederates back for several hours in hand - to - hand combat . Mahone ' s Confederates conducted a sweep out of a sunken gully area about from the right side of the Union advance . This charge reclaimed the earthworks and drove the Union force back towards the east . In later stages of the battle , many Union casualties were black soldiers killed by Confederate bayonets and musket fire even after surrendering – a direct violation of the rules of war prevalent at the time ( the Lieber Code ) . At the same time , black soldiers were also bayoneted by white Union soldiers who feared reprisal from victorious CSA troops . Aftermath . Union casualties were 3 , 798 ( 504 killed , 1 , 881 wounded , 1 , 413 missing or captured ) , Confederate 1 , 491 ( 361 killed , 727 wounded , 403 missing or captured ) . Many of the Union losses were suffered by Ferrero ' s division of the USCT . Both the black and white wounded prisoners were taken to the Confederate hospital at Poplar Lawn in Petersburg . Meade brought charges against Burnside , and a subsequent court of inquiry censured Burnside along with Brig . Gens . Ledlie , Ferrero , Orlando B . Willcox , and Col . Zenas R . Bliss . Burnside was never again assigned to duty . Although he was as responsible for the defeat as Burnside , Meade escaped immediate censure . However , in early 1865 , the Congressional Joint Committee on the Conduct of the War exonerated Burnside and condemned Meade for changing the plan of attack ( which did little good for Burnside , whose reputation was ruined ) . As for Mahone , the victory , won largely due to his efforts in supporting Johnson ' s stunned men , earned him a lasting reputation as one of the best young generals of Lee ' s army in the war ' s last year . Grant wrote to Chief of Staff Henry W . Halleck , " It was the saddest affair I have witnessed in this war . " He also stated to Halleck that " Such an opportunity for carrying fortifications I have never seen and do not expect again to have . " Pleasants , who had no role in the battle itself , received praise for his idea and the execution thereof . When he was appointed a brevet brigadier general on March 13 , 1865 , the citation made explicit mention of his role . Grant subsequently gave in his evidence before the Committee on the Conduct of the War : Despite the battle being a tactical Confederate victory , the strategic situation in the Eastern Theater remained unchanged . Both sides remained in their trenches and the siege continued . Historical site . The area of the Battle of the Crater is a frequently visited portion of Petersburg National Battlefield Park . The mine entrance is open for inspection annually on the anniversary of the battle . There are sunken areas where air shafts and cave - ins extend up to the " T " shape near the end . The park includes many other sites , primarily those that were a portion of the Union lines around Petersburg . In popular media . The Battle of the Crater was graphically portrayed in the opening scenes of the 2003 film Cold Mountain starring actor Jude Law as a Confederate soldier / deserter .