Burnside waited at his headquarters to hear that Meade had successfully driven Jackson back. When no word of this came, he ordered the attack on Marye's Heights to go ahead anyway. Artillery on top of Marye's Heights and nearby hills would prevent any assault on the Heights. But Sumner ordered a series of attacks all afternoon with the Confederate artillery raining down shells on them. Finally, at dusk the attacks were called off. One after another, three divisions had tried to scale Marye's Heights and all had failed. Nearly 3,000 men were lost in just an hour but the attacks continued with no effect. As Lee watched the destruction of Sumner's divisions he remarked, "It is well that war is so terrible. We should grow too fond of it." Of the 12,600 Federal casualties almost two-thirds were lost assaulting Marye's Heights. In turn, the Confederates lost about 5,000 men during the battle.