After the Confederates retreated into Vicksburg earthworks their lines were nearly impregnable. Grant tried twice to break through the lines which ended in disaster. The Union Army began digging tunnels under the Confederate lines in order to place explosives to blow a hole in the Confederate earthworks. On June 25 they set off a charge that consisted of 2,200 pounds of gunpowder. A Confederate soldier left the following account. "A huge mass of earth suddenly, and with tremendous force and terrific explosion, flew upwards, descending with mighty power upon the gallant defenders, burying numbers beneath it's falling fragments, bruising and mangling them most horribly. It seemed as if all hell had suddenly yawned upon the devoted band, and vomited forth it's sulphurous fire and smoke upon them." Although the Confederate lines had been breached the Union attack failed. On July 1st another charge was set off in the same area. The Confederates had slaves digging counter tunnels trying to find the Union tunnels because they were able to hear the sound of digging. The explosion killed most of the slaves but a slave named Abraham was blown high into the air landing on his back in Union lines. With the exception of bruising on the back of his head and shoulders, which took the greatest impact upon landing in soft dirt, he was okay. Again the Union attack failed but it didn't matter because Pemberton surrendered three days later. The first picture is the area of the explosion at Vicksburg today and a picture of Abraham.