Successful as these devices were in halting the Union advance, Lee was aware that an infantry charge would be necessary to dislodge the enemy. By 6 a.m. an order had gone out to Brig. Gen. William Mahone to move two brigades of his division from the lines south of Petersburg to the defense of the threatened position; Mahone had anticipated the order and already had his troops in motion. Then Lee joined Beauregard in observing the battle from the Gee house, 500 yards to the rear of the scene of action. [Illustration: _Colonel Pleasants’ sketch of the Crater._] _Outline of Crater._ _Course of Confederate Works._ _S & E_ _Magazines._ In spite of the Confederate resistance, part of the Northern black division and other regiments had, by 8 a.m., advanced a short distance beyond their companions at the crater. Shortly thereafter, Mahone’s lead Confederate brigade arrived on the scene. The men filed into a ravine about 200 yards northwest of the crater and between it and Petersburg. No sooner had they entered this protected position than, perceiving the danger to their lines, they charged across the open field into the mass of Federal soldiers. Although outnumbered, they forced the Northerners to flee back to the comparative shelter of the crater. Then they swept on to regain a portion of the line north of the Union-held position. [Illustration: _To many soldiers, the explosion of the mine and the bitter Battle of the Crater that followed were the most memorable events of the siege. Artist A. R. Waud sketched the explosion from the Union lines._] By 10:30 another of Mahone’s brigades had reached the point of danger, and it charged the Union troops holding the crater, only to be repulsed. Meanwhile, the lot of the Northern soldiers was rapidly becoming unbearable. Confederate artillery continued to beat upon them. The closely packed troops (dead, dying, and living indiscriminately mixed) lacked shade from the blazing sun, food, water and, above all, competent leadership. Meade had ordered their withdrawal more than an hour before the second Confederate charge, but Burnside delayed the transmission of the order till after midday. Many men had chosen to run the gantlet of fire back to their own lines, but others remained clinging to the protective sides of the crater.