On the side of the Tennessee River, over against Pittsburg Landing, are some low bare hills, partly inclosed by a forest. In the dusk of the evening of April 6 this open space, as seen from the other side of the stream--whence, indeed, it was anxiously watched by thousands of eyes, to many of which it grew dark long before the sun went down--would have appeared to have been ruled in long, dark lines, with new lines being constantly drawn across. These lines were the regiments of Buell's leading division, which having moved up from Savannah through a country presenting nothing but interminable swamps and pathless "bottom lands," with rank overgrowths of jungle, was arriving at the scene of action breathless, footsore and faint with hunger. It had been a terrible race; some regiments had lost a third of their number from fatigue, the men dropping from the ranks as if shot, and left to recover or die at their leisure. Nor was the scene to which they had been invited likely to inspire the moral confidence that medicines physical fatigue. True, the air was full of thunder and the earth was trembling beneath their feet; and if there is truth in the theory of the conversion of force, these men were storing up energy from every shock that burst its waves upon their bodies. Perhaps this theory may better than another explain the tremendous endurance of men in battle. But the eyes reported only matter for despair. Before us ran the turbulent river, vexed with plunging shells and obscured in spots by blue sheets of low-lying smoke. The two little steamers were doing their duty well. They came over to us empty and went back crowded, sitting very low in the water, apparently on the point of capsizing. The farther edge of the water could not be seen; the boats came out of the obscurity, took on their passengers and vanished in the darkness. But on the heights above, the battle was burning brightly enough; a thousand lights kindled and expired in every second of time. There were broad flushings in the sky, against which the branches of the trees showed black. Sudden flames burst out here and there, singly and in dozens. Fleeting streaks of fire crossed over to us by way of welcome. These expired in blinding flashes and fierce little rolls of smoke, attended with the peculiar metallic ring of bursting shells, and followed by the musical humming of the fragments as they struck into the ground on every side, making us wince, but doing little harm. The air was full of noises. To the right and the left the musketry rattled smartly and petulantly; directly in front it sighed and growled. To the experienced ear this meant that the death-line was an arc of which the river was the chord. There were deep, shaking explosions and smart shocks; the whisper of stray bullets and the hurtle of conical shells; the rush of round shot. There were faint, desultory cheers, such as announce a momentary or partial triumph.