4:45 a.m. - 6:00 a.m.
On the morning of July 30th, 1864, the Union high command became anxious as to why the mine under the Confederate position, had not been sprung. While General Meade was sending dispatches to General Burnside asking when the mine would detonate, at 4:15 a.m. Colonel Pleasants, of the 48th Pennsylvania, allowed Sgt. Reese, soon followed by Lt. Douty to go in the mine, (to your front) and investigate the fuse. As it turned out, the faulty fuse had extinguished at a splice over half way to the powder magazines at the end of the mine. Once the two soldiers succeeded in relighting the fuse, they reported to Pleasants that it would take no more that fifteen minutes for the powder to touch off.
At 4:45 a.m., Howard Aston of the 13th Ohio Cavalry reported, "A trembling of the earth was felt and a dull roar was heard. I looked to the front and saw a huge column of dirt, dust, smoke, and flame of fire apparently 200 feet high... while in the air I could see in the column of fire... bodies of men... timber and a gun carriage." Approximately two hundred and sixty Confederates were blow up and buried under the debris of the explosion. As the debris from the mine settled, the Union artillery opened upon the Confederates with about 150 pieces of cannons and mortars. These guns were soon answered by the Confederate artillery and the shriek and howl of solid shot and shell soon filled the air.
As Colonel Marshall's brigade cleared the Union earthworks in front of you, they advanced across no man's land, toward the enormous hole that was seething with smoke. They observed that it was filled " with dust, great blocks of clay, guns... and men buried in various ways." While the lead elements of Marshall's brigade made their way into the crater, they became rescue parties and started to dig out the buried Confederates. This action slowed the advance of the Union brigades and blocked the path to the heights beyond the crater. The 2nd Pennsylvania Provisional Heavy Artillery, however, was able to rush through the crater, get over the loose dirt, and reform among the bombproofs to the rear of the demolished sailent. At this point, Confederate infantry regrouped on the flanks of the Union soldiers and began to pour a light but persistent fire into the flank and rear of the men in the crater. This caused commands here and elsewhere in the crater to become quickly intermingled and confused.
Additional Union brigades would continue to file out of the covered ways and try and force their way through the Confederate line of trenches and bombproofs. As the crater became more crowded, regiments would try and push to the left and right of the pit in hopes of breaking through the Confederate line. Burnside's worst fears were coming true. Instead of pushing for the Jerusalem Plank Road and Cemetery Hill, the Union brigades were starting to dig in and hold the position.
The sketch by Alfred R. Waud (left) depicts Union soldiers filing through the covered ways and over the Union picket line towards the crater, which is to your front. The map (above) illustrates Union and Confederate movements after the mine was exploded during the early morning hours of July 30, 1864.