Doc. 43.-the battle of Chickamauga.
Report of Major-General Rosecrans.
the rebel army, after its expulsion from Middle Tennessee, crossed the Cumberland Mountains by way of the Tantallon and University roads, then moved down Battle Creek, and crossed the Tennessee River on bridges, it is said, near the mouth of Battle Creek, and at Kelly's Ferry, and on the railroad bridge at Bridgeport. They destroyed a part of the latter, after having passed over it, and retired to Chattanooga and Tyner Station, leaving guards along the river. On their arrival at Chattanooga, they commenced immediately to throw up some defensive field-works at that place, and also at each of the crossings of the Tennessee as far up as Blythe's Ferry. Our troops, having pursued the rebels as far as supplies and the state of the roads rendered it practicable, took position from McMinnville to Winchester, with advances at Pelham and Stevenson. The latter soon after moved to Bridgeport in time to save from total destruction a saw-mill there, but not to prevent the destruction of the railroad bridge. After the expulsion of Bragg's forces from Middle Tennessee, the next objective point of this army was Chattanooga. It commands the southern entrance into East-Tennessee, the most valuable, if not the chief sources of supplies of coal for the manufactories and machine-shops of the Southern States, and is one of the great gateways through the mountains to the champaign counties of Georgia and Alabama. For the better understanding of the campaign, I submit a brief outline of the topography of the country, from the barrens of the north-western base of the Cumberland Range to Chattanooga and its vicinity. The Cumberland Range is a lofty mass of rocks separating the waters which flow into the Cumberland from those which flow into the Tennessee, and extending from beyond the Kentucky line, in a south-westerly direction, nearly to Athens, Alabama. Its north-western slopes are steep and rocky, and scalloped into coves, in which  are the heads of. numerous streams that water Middle Tennessee. Its top is undulating, or rough, covered with timber, soil comparatively barren, and in dry seasons scantily supplied with water. Its south-eastern slope, above Chattanooga, for many miles, is precipitous, rough, and difficult all the way up to Kingston. The valley between the foot of this slope and the river seldom exceeds four or five miles in width, and, with the exception of a narrow border along the banks, is undulating or hilly. The Sequatchie Valley is along the river of that name, and is a canon, or deep cut, splitting the Cumberland Range parallel. It is only three or four miles in breadth and fifty in length. The sides of this valley are even more precipitous than the great eastern and western slopes of the Cumberland, which have just been described. To reach Chattanooga from McMinnville, or north of the Tennessee, it is necessary to turn the head of this valley by Pikeville and pass down the Valley of the Tennessee, or to cross it by Dunlap or Thurman. That part of the Cumberland Range between Sequatchie and the Tennessee, called Walden's Ridge, abuts on the Tennessee, in high, rocky bluffs, having no practicable space sufficient for a good wagon-road along the river. The Nashville and Chattanooga Railroad crosses that branch of the Cumberland Range, west of the Sequatchie, through a low gap, by a tunnel, two miles east of Cowan, down the gorge of Big Crow Creek to Stevenson, at the foot of the mountain, on the Memphis and Charleston Railroad, three miles from the Tennessee and ten from Bridgeport. Between Stevenson and Chattanooga, on the south of the Tennessee, are two ranges of mountains, the Tennessee River separating them from the Cumberland. Its channel, a great chasm cut through the mountain masses, which in those places abut directly on the river. These two ranges are separated by a narrow valley through which runs Lookout Creek. The Sand Mountain is next the Tennessee, and its northern extremity is called Raccoon Moun tain. Its sides are precipitous and its top barren oak ridges, nearly destitute of water. There are but few, and those very difficult, wagon-roads by which to ascend and descend the slopes of this mountain. East of Lookout Valley is Lookout Mountain, a vast palisade of rocks rising two thousand four hundred feet above the level of the sea, in abrupt, rocky cliffs, from a steep, wooded base. Its eastern sides are no less precipitous. Its top varies from one to six or seven miles in breadth, is heavily timbered, sparsely settled, and poorly watered. It terminates abruptly upon the Tennessee, two miles below Chattanooga, and the only practical wagon-roads across it, are over the nose of the mountain, at this point, one at Johnson's Crook, twenty-six miles distant, and one at Winston's Gap, forty-two miles distant from Chattanooga. Between the eastern base of this range, and the line of the Chattanooga and Atlanta or Georgia State Railroad are a series of narrow valleys, separated by smaller ranges of hills or low mountains, over which there are quite a number of practicable wagon-roads running eastward toward the railroad. The first of these ranges is Missionary Ridge, separating the waters of Chickamauga from Chattanooga Creek. A higher range with fewer gaps, on the southeast side of the Chickamauga, is Pigeon Mountain, branching from Lookout, near Dougherty's Gap, some forty miles south from Chattanooga. It extends in a northerly direction, bearing eastward, until it is lost in the general level of the country near the line of the Chattanooga and La Fayette road. East of these two ranges and of the Chickamauga, starting from Ottowah and passing by Ringgold, to the west of Dalton, is Taylor's Ridge, a rough, rocky range, traversable by wagon-roads only, through gaps generally several miles apart. Missionary Ridge passes about three miles east of Chattanooga, ending near the Tennessee at the mouth of the Chickamauga. Taylor's Ridge separates the East-Tennessee and Georgia Railroad from the Chattanooga and Atlanta Railroad. The junction of these roads is at Dalton, in a valley east of Taylor's Ridge, and west of the rough mountain region, in which are the sources of the Cossa River. This valley, only about nine or ten miles wide, is the natural southern gateway into East-Tennessee, while the other valleys just mentioned terminate northwardly on the Tennessee to the west of it, and extend in a southwesterly direction toward the line of the Cossa, the general direction of which, from the crossing of the Atlanta road to Rome and thence to Gadsden, is south-west. From the position of our army at McMinnville, Tullahoma, Decherd, and Winchester, to reach Chattanooga, crossing the Tennessee above it, it was necessary, either to pass north of the Sequatchie Valley, by Pikesville or Kingston, or to cross the main Cumberland and the Sequatchie Valley by Dunlap or Thurman and Walden's Ridge, by the routes passing through these places, a distance from sixty-five to seventy miles, over a country destitute of forage, poorly supplied with water, by narrow and difficult wagon-roads. The main Cumberland Range could also have been passed, on an inferior road, by Pelham and Tracy City to Thurman. The most southerly route on which to move troops and transportation to the