By 9 o'clock on the morning of September 22 my command took up a position within the heavy line of intrenchments at Chattanooga, the greater part of which defenses had been thrown up since the army commenced arriving there the day before. The enemy, having now somewhat recovered from the shock of the recent battle, followed carefully, and soon invested us close into our lines with a parallel system of rifle-pits. He also began at once to erect permanent lines of earthworks on Missionary Ridge and to establish himself strongly on Lookout Mountain. He then sent Wheeler's cavalry north of the Tennessee, and, aided greatly by the configuration of the ground, held us in a state of partial siege, which serious rains might convert into a complete investment. The occupation of Lookout Mountain broke our direct communication with Bridgeport-our sub-depot—and forced us to bring supplies by way of the Sequatchie Valley and Waldron's Ridge of the Cumberland Mountains, over a road most difficult even in the summer season, but now liable to be rendered impassable by autumn rains. The distance to Bridgeport by this circuitous route was sixty miles, and the numerous passes, coves, and small valleys through which the road ran offered tempting opportunities, for the destruction of trains, and the enemy was not slow to take advantage of them. Indeed, the situation was not promising, and General Rosecrans himself, in communicating with the President the day succeeding the battle of Chickamauga, expressed doubts of his ability to hold the gateway of the Cumberland Mountains.