Headquarthrs 14tii Aiuiy Corps, ? MuRFREESBoiio, Jan. 7, 1863. There can be do místate that in coolness, readiness, fertüity of resource, celcrify of tiiought and decisión, and comprehensivo grasp of mind in the most trying situations of peril, personal and military, General Rosecrans, on the 31st of December, proved hiinsclf perfectly equal to the tremendous responsibility whieh devolved upon him. You rarely find practical skill, profound strategy, and executive faculty. with a mind which grasps general principies, and eagerly inquires into, and handles remóte details, einbodied m one character, and yet General Rosecrans has demonstrated that he oombir.es all. ,' When his right wing was so astoundingly thrown back into his face with frightful rapidity and violenco, it was enough to have shaken any ordinary mind. It must have toucbed him nearly. ITis plans wcre so thoroughly preparey and digested, and so woll approved by his best Generáis - he relied so earneítld upon the stuunchncss of the, till then, trusty right wing - that the pang of disappointmeut, when it gave way with so little resÍBtancé, must have been almost crushiDtr for the instant. But he scarce made a sign. A little color, perhaps, faded froua his face, but he dashed away omotion with a gesture of impatience, and veheinently said, " Never mind - never mind - we will reetify it- we will makc it all right." Frotn that instant uo man discerned a glimmer of despondoncy, uucertainty, or vacillation in his features, tone, deportment, bufe he bent the whole force of his will, and dirceted all the powers of his ready and fertile mind iuto that field, with au obvious de tcroiination to make it his own. These were the observa'ions of many who watuhed him all day long with the koenest and most painful solicitude. The íaintest jjelaxation of his constanoy would have unmsnned us all. Here was a real picture of greatness which I had never looked upon before. It is vvell to examine the plan again, to discover how it was marred. The right wing, with tbreo divisions, was to hold the euemy in check, whilo the left wing was to swing around behind the enemy, and cut off his retreat. A third división was to be hurled against tbe right, and break it off at its flank, by "surprise." The moveinent of the left was thus paralyzed, and its whole power was esseutial to tbe preservation of the army It was gathered up matchlessly, jind flung into the right wing, under fire, in the face of a victorious mass of the enemy, and with it he fouud an entirely new line of battle to resist - powerful columns, which were rushing upon the new line. To chance front in the face of the enemy, under any circumstance, is regarded by military authorities an extremely hazardous manoeuvre, but to form an entirely new line in the face of the enemy, while the original is flying before it, and to repel that victorious enemy with it, may coolly be characterized extraordinary. I3ut this was scarcely more admirable tlian the skill then and subsequeutly displayed in the handling of troops and ar tillery. Of course this was facilitated by the discipline of the ármy, and the able seconding of others; but the direct ageney of the General himself was too conspicuous to be gainsaid. After the raisfortune upon the right, the whole army was massed in doublé columns, by divisions, in the center, and was impregnable at every point. Linea upon lines of troops wera piled upon each other so compactly that the whole power of the enemy couid not make a serious impres sion upon any point of it. The artillery was handled as if it were a pocket pistol, and troops in masses were hurled across the field as if thcy were a g-eat ball tossed about by a. Titan. The commonest soldiers observed it with audible expressions of admiration. In the heat of a desperate attack, a brigade was moved across the field swiftly, to meet a demonstration at another point. One of our forty or fifty thousaud private Generáis - you kuow our lads are all Generáis - wanted to know of another in the moving brigade, "What tbe are you going over there for? It's botas ïiere; why don't you support us ?" "Going where Old Rosey wants us. He knows what he's up to," was the reply. The blaze and uproar of artillery, massed in battery of twelve, twenty or more guns, and its manifest effectiveness, and the moveinent of masses upon that leid, was a spectacle of appalling sublimïty as well as an examplo of admirable martial art. Major General Thomas is a regular salamander. Ilis corps was in the center. Oí course he was with it. While ;be oighth división was fighting staunchy, he was there to assist Ñegley. When Llousseau got into the woods, and was oriléred out again uiu'er a storm of mis siles, Tilomas was at band to give directions, and when he got out himself he ran the gauntlet of cross-firing, and, strangely enough, was not eveu scratched. I saw 10 ditt'erenco between his deportment under fie and in his marquee. The coutrust between him and Rousseau was striking. One was imperturbable ; the other blazed like a cornet, inspiring wild enthusiasm ainong his faithful troops. Crittenden was perfectly calm, but there was au unusual stateliness in his deportment that expressed his consciousness of a great battlo. He made no noise about his coininand, but hè was confident it would justify his proudest expectations when it bhould engage. It did its duty uobly. General McCook I did not see when his comrnand was engnged. Later 'm the day-r-it was pretty hot, too - he was ncar the left of his line, surrounded by his stafl' - Bassett, Laogdon, ('ampbull, iiams, Threuston, Fishcr, Caeb, ' a littlc flushed by excitement and fatigue, but otherwise as you see him oustomarily. The horsB lie rode would not moet your notions of a "charger," sinoe he bad accepted, as KDg llichard did, "anotber" horse in 1-ieu of the fine stced which had becu killed under hira.