on May 13, the exhausted Confederate infantrymen were notified that the new line was ready, and they withdrew from the original earthworks unit by unit. The combat they had endured for almost 24 hours was characterized by an intensity of firepower never previously seen in Civil War battles, as the entire landscape was flattened, all the foliage destroyed. May 12 was the most intensive day of fighting during the battle, with Union casualties of about 9,000, Confederate 8,000; the Confederate loss includes about 3,000 prisoners captured in the Mule Shoe. Despite the significant casualties of May 12, Grant was undeterred. He planned to reorient his lines and shift the center of potential action to the east of Spotsylvania, where he could renew the battle. He ordered the V and VI Corps to move behind the II Corps and take positions past the left flank of the IX Corps. On the night of May 13–14, the corps began a difficult march in heavy rain. Grant notified Washington that, having endured five days of almost continuous rain, his army could not resume offensive operations until they had 24 hours of dry weather. The weather finally cleared on May 17. Grant ordered the II Corps and the VI Corps to attack against the Mule Shoe area again at sunrise, May 18. Unfortunately for the Union plan, the former Confederate works were still occupied by Ewell's Second Corps and they had used the intervening time to improve the earthworks and the obstacles laid out in front of them. Unlike on May 12, they were not caught by surprise. As Hancock's men advanced, they were caught up in abatis and subjected to artillery fire so devastating that infantry rifle fire was not necessary to repulse the attack. Wright and Burnside had no better luck in supporting attacks. Grant decided to abandon the Spotsylvania area. He ordered Hancock's II Corps to march to the railroad line between Fredericksburg and Richmond, and then turn south. With luck, Lee might take the bait and follow, seeking to overwhelm and destroy the isolated corps. In that case, Grant would chase Lee with his remaining corps and strike him before the Confederates could entrench again. Before Hancock began to move, Lee ordered Ewell to conduct a reconnaissance in force to locate the northern flank of the Union army. Ewell fought near the Harris farm with several units of Union heavy