The massive casualties sustained in the campaign were damaging to the Northern war effort. The price of gold almost doubled and Abraham Lincoln's prospects for reelection were put into jeopardy. It was only the later successes at Mobile Bay, the Shenandoah Valley, and Sherman's capture of Atlanta, that turned Northern morale and the political situation around. Grant's reputation also suffered. The knowledge that he could more easily afford to replace his losses of men and equipment than Lee may have influenced Grant's strategy. However, historians do not agree that Grant deliberately engaged in numerous attacks merely to defeat Lee solely through attrition, without regard for the losses to his army, needlessly throwing lives away in fruitless frontal assaults to bludgeon Lee. The overall strategy of the Overland Campaign depended on using Grant's numerical superiority to allow progressive shifts to the left by "spare" Union corps while Confederate forces were relatively pinned in their positions by the remaining Union forces. Such a strategy could not succeed without the continuing threat of defeat by direct assault in each of the positions assumed by Lee's army. The strategy failed in that Lee, possessing shorter lines of march (being nearer to Richmond, which was also his base), was able to prevent Grant's forces getting between Lee and Richmond, but was effective in allowing Grant to draw progressively closer to Richmond up to the battle at Cold Harbor. There, with the barrier of the James River and estuary to his left, Grant did not have the room necessary to continue such movements. He had to choose one among three possibilities: attack, shift to the right and thus back toward Washington, or cross the James to get at Lee's supply lines. He attempted the first, then did the third, as the second was unacceptable.