THE LAST EFFORT. _Friday, July 3._--The sun rose bright and warm, and looked down upon the blackened corpses of the dead, which were strewn over the bloody earth; upon the wounded who had not been cared for, and upon long glistening lines of armed men, ready to renew the conflict. Each antagonist, rousing every slumbering element of power, seemed to be resolved upon victory or death. The fight commenced early by an attack of General Slocum's men, who, determined to regain the rifle-pits they had lost the evening before, descended like an avalanche upon the foe. The attack met with a prompt response from General Ewell. But after several hours of desperate fighting, victory perched upon the Union banners, and with great loss and slaughter the Rebels were driven out of the breastworks, and fell back upon their main lines near Benner's Hill. This successful move on the part of our boys in blue was followed by ominous lull or quiet, which continued about three hours. Meanwhile the silence was fitfully broken by an occasional spit of fire, while every preparation was being made for a last, supreme effort, which, it was expected, would decide the mighty contest. The scales were being poised for the last time, and upon the one side or the other was soon to be written the "_Mene, Mene, Tekel, Upharsin_." Hearts either trembled or waxed strong in the awful presence of this responsibility. At length one o'clock arrived; a signal-gun was fired, and then at least one hundred and twenty-five guns from Hill and Longstreet concentrated and crossed their fires upon Cemetery Hill, the centre and key of our position. Just behind this crest, though much exposed, were General Meade's headquarters. For nearly two hours this hill was ploughed and torn by solid shot and bursting shell, while about one hundred guns on our side, mainly from this crest and Round Top, made sharp response. The earth and the air shook for miles around with the terrific concussion, which came no longer in volleys, but in a continual roar. So long and fearful a cannonade was never before witnessed on this continent. As the range was short and the aim accurate, the destruction was terrible. But the advantage was decidedly in favor of the Rebels, whose guns were superior in number to ours, and of heavier calibre, and had been concentrated for the attack. A spectator of the Union army thus describes the scene: