2. We move to-morrow, at six o'clock in the morning, to Nashville.

9. Nashville. Every thing indicates an early movement. Whether a reconnoissance is intended or a permanent advance, I do not even undertake to guess. The capture of a brigade, at Hartsville, by John Morgan, has awakened the army into something like life; before it was idly awaiting the rise of the Cumberland, but this bold dash of the rebels has made it bristle up like an angry boar; and this morning, I am told, it starts out to show its tusks to the enemy. Our division has been ordered to be in readiness.

The kind of weather we desire now, is that which is generally considered the most disagreeable, namely, a long rain; two weeks of rain-fall is necessary to make the Cumberland navigable, and thus ensure to us abundant supplies.

The whole army feels deeply mortified over the loss of the brigade at Hartsville; report says it was captured by an inferior force. One of our regiments did not fire a gun, and certainly the other two could not have made a very obstinate resistance. I am glad Ohio does not have to bear the whole blame; two-thirds is rather too much.

10. During all of the latter part of last night troops were pouring through Nashville, and going southward. Our division, Rousseau's, moved three miles beyond the city, and went into camp on the Franklin road.

14. Our court has been holding its sessions in the city, but to-day it adjourned to meet at division head-quarters to-morrow at ten o'clock a. m.

The most interesting character of our court-martial is Colonel H. C. Hobart, of the Twenty-first Wisconsin; a gentleman who has held many important public positions in his own State, and whose knowledge of the law, fondness for debate, obstinacy in the maintenance of his opinions, love of fun, and kind-heartedness, are immense. He makes use of the phrase, "in my country," when he refers to any thing which has taken place in Wisconsin; from this we infer that he is a foreigner, and pretend to regard him as a savage from the great West. He has, therefore, been dubbed Chief of the Wisconsins. The court occasionally becomes exceedingly mellow of an evening, and then the favorite theme is the "injin." Such horrible practices as dog eating and cannibalism are imputed to the Chief. To-night we visited the theater to witness Ingomar. On returning to our room at Bassay's restaurant, the members took solemn Irish oaths that the man with the sheep-skin on his back, purporting to be Ingomar, was no other than Hobart, the Wisconsin savage; and the supposition that such an individual could ever reform, and become fitted for civilized society, was a monstrous fiction, too improbable even for the stage.

It should not be presumed from this, however, that the subject of our raillery holds his tongue all the time. On the contrary, he expresses the liveliest contempt for the opinions of his colleagues of the court-martial, and professes to think if it were not for the aid which the Nation receives from his countrymen, the Wisconsins, the effort to restore the Union would be an utter failure.

Bassay's restaurant is a famous resort for military gentlemen. Major-General Hamilton just now took dinner; Major-General Lew Wallace, Brigadier-Generals Tyler and Schoepf, and Major Donn Piatt occupy rooms on the floor above us, and take their meals here; so that we move in the vicinity of the most illustrious of men. We are hardly prepared now to say that we are on intimate terms with the gentlemen who bear these historic names; but we are at least allowed to look at them from a respectful distance. A few years hence, when they are so far away as to make contradiction improbable, if not impossible, we may claim to have been their boon companions, and to have drank and played whist with them in the most genial and friendly way.

16. This afternoon Negley sent over a request for help, stating that his forage train had been attacked. The alarm, however, proved groundless. A few shots only had been fired at the foragers.

17. The news from Fredericksburg has cast a shadow over the army. We did hope that Burnside would be successful, and thus brighten the prospect for a speedy peace; but we are in deeper gloom now than ever. The repulse at Fredericksburg, while it has disabled thousands, has disheartened, if not demoralized a great army, and given confidence and strength to the rebels every-where. It may be, however, that this defeat was necessary to bring us clearly to the point of extinguishing slavery in all the States. The time is near when the strength of the President's resolution in this regard will be put to the test. I trust he will be firm. The mere reconstruction of the Union on the old basis would not pay humanity for all the blood shed since the war began. The extinction of slavery, perhaps, will.

While the North raises immense numbers of men, and scatters them to the four winds, the enemy concentrates, fortifies, and awaits attack. Will the man ever come to consolidate these innumerable detachments of the National army, and then sweep through the Confederacy like a tornado?

It is said that many regiments in the Eastern army number less than one hundred men, and yet have a full complement of field and company officers. This is ridiculous; nay, it is an outrage upon the tax-payers of the North. Worse still, so long as such a skeleton is called a regiment, it is likely to bring discredit upon the State and Nation; for how can it perform the work of a regiment when it has but one-tenth of a regiment's strength? These regiments should be consolidated, and the superfluous officers either sent home or put into the ranks.

20. This morning, at one o'clock, we were ordered to hold ourselves in readiness to march at a moment's notice, with five days' rations. Court has adjourned to meet at nine o'clock a. m. Monday. It is disposing of cases quite rapidly, and I think next week, if there be no interruptions, it will be able to clear the docket.

A brigade, which went out with a forage train yesterday, captured a Confederate lieutenant at a private house. He was engaged at the moment of his capture in writing a letter to his sweetheart. The letter was headed Nashville, and he was evidently intent upon deceiving his lady-love into the belief that he had penetrated the Yankee lines, and was surrounded by foes. Had the letter reached her fair hands, what earnest prayers would have gone up for the succor of this bold and reckless youth.

There was a meeting of the generals yesterday, but for what purpose they only know.

21. The dispatches from Indianapolis speak of the probable promotion of Colonel Jones, Forty-second Indiana. This seems like a joke to those who know him. He can not manage a regiment, and not even his best friends have any confidence in his military capacity. In Indiana, however, they promote every body to brigadierships. Sol Meredith, who went into the service long after the war began, and who, in drilling his regiment, would say: "Battalion, right or left face, as the case may be, march," was made a brigadier some time ago. Milroy, Crittenden, and many others were promoted for inconsiderable services in engagements which have long since been forgotten by the public. Their promotions were not made for the benefit of the service, but for the political advancement of the men who caused them to be made.

Last evening, a little after dark, we were startled by heavy cannonading on our left, and thought the enemy was making an attack. The boys in our division were all aglow with excitement, and cheered loudly; but after ten or fifteen minutes the firing ceased, and I have heard no more about it.

The rebels are before us in force. The old game of concentration is probably being played. The repulse of our army at Fredericksburg will embolden them. It will also enable them to spare troops to reinforce Bragg. The Confederates are on the inside of the circle, while we are on the outside, scattered far and wide. They can cut across and concentrate rapidly, while we must move around. They can meet Burnside at Fredericksburg, and then whip across the country and face us, thus making a smaller army than ours outnumber us in every battle.

In the South the army makes public opinion, and moves along unaffected by it. In the North the army has little or nothing to do with the creation of public sentiment, and yet is its servant. The people of the North, who were clamoring for action, are probably responsible for the fatal repulse at Fredericksburg and the defeat at Bull run. The North must be patient, and get to understand that the work before us is not one that can be accomplished in a day or month. It should be pushed deliberately, yet persistently. We should get rid of a vast number of men who are forever in hospital. They are an expense to the country, and an incumbrance to the army. We should consolidate regiments, and send home thousands of unnecessary officers, who draw pay and yet make no adequate return for it.

23. The court met this morning as usual. We are now going on the fifth week of the session. New cases arise just about as fast as old ones are disposed of.

The boys in front of my tent are singing:

Were they to devote as much time to praying as they do to singing, they would soon establish a reputation for piety; but, unfortunately for them, after the hymn they generally proceed to swear, instead of prayer, and one is left in doubt as to what home they propose to go to.

25. About noon there were several discharges of artillery in our front, and last night occasional shots served as cheerful reminders that the enemy was near.

At an expense of one dollar and seventy-five cents, I procured a small turkey and had a Christmas dinner; but it lacked the collaterals, and was a failure.

For twenty months now I have been a sojourner in camps, a dweller in tents, going hither and yon, at all hours of the day and night, in all sorts of weather, sleeping for weeks at a stretch without shelter, and yet I have been strong and healthy. How very thankful I should feel on this Christmas night! There goes the boom of a cannon at the front.

26. This morning we started south on the Franklin road. When some ten miles away from Nashville, we turned toward Murfreesboro, and are now encamped in the woods, near the head-waters of the Little Harpeth. The march was exceedingly unpleasant. Rain began to fall about the time of starting, and continued to pour down heavily for four hours, wetting us all thoroughly.

I have command of the brigade.

27. We moved at eight o'clock this morning, over a very bad dirt road, from Wilson's pike to the Nolansville road, where we are now bivouacking. About ten the artillery commenced thundering in our front, and continued during the greater portion of the day. Marched two miles toward Triune to support McCook, who was having a little bout with the enemy; but the engagement ending, we returned to our present quarters in a drenching rain. Saw General Thomas, our corps commander, going to and returning from the front. We are sixteen miles from Nashville, on a road running midway between Franklin and Murfreesboro. The enemy is supposed to be in force at the latter place.

28. At four o'clock p. m. we were ordered to leave baggage and teams behind, and march to Stewart's creek, a point twenty miles from Nashville. Night had set in before the brigade got fairly under way. The road runs through a barren, hilly, pine district, and was exceedingly bad. At eleven o'clock at night we reached the place indicated, and lay on the damp ground until morning.

29. At eight o'clock a. m. the artillery opened in our front; but after perhaps two hours of irregular firing, it ceased altogether, and we were led to the conclusion that but few rebels were in this vicinity, the main body being at Murfreesboro, probably. Going to the front about ten o'clock, I met General Hascall. He had had a little fight at Lavergne, the Twenty-sixth Ohio losing twenty men, and his brigade thirty altogether. He also had a skirmish at this place, in which he captured a few prisoners. Saw General Thomas riding to the front. Rosecrans is here, and most of the Army of the Cumberland either here or hereabouts. McCook's corps had an inconsiderable engagement at Triune on Saturday. Loss small on both sides.

Riding by a farm-house this afternoon, I caught a glimpse of Miss Harris, of Lavergne, at the window, and stopped to talk with her a minute. The young lady and her mother have experienced a great deal of trouble recently. They were shelled out of Lavergne three times, two of the shells passing through her mother's house. She claims to have been shot at once by a soldier of the One Hundred and Nineteenth Illinois, the ball splintering the window-sill near her head. Her mother's house has been converted into a hospital, and the clothes of the family taken for bandages. She is, therefore, more rebellious now than ever. She is getting her rights, poor girl!

30. A little after daylight the brigade moved, and proceeded to within three miles of Murfreesboro, where we have been awaiting orders since ten o'clock a. m.

The first boom of artillery was heard at ten o'clock. Since then there has been almost a continuous roar. McCook's corps is in advance of us, perhaps a mile and a half, and, with divisions from other corps, has been gradually approaching the enemy all day, driving his skirmishers from one point to another.

About four o'clock in the afternoon the artillery firing became more vigorous, and, with Colonel Foreman, of the Fifteenth Kentucky, I rode to the front, and then along our advanced line from right to left. Our artillery stationed on the higher points was being fired rapidly. The skirmishers were advancing cautiously, and the contest between the two lines was quite exciting. As I supposed, our army is feeling its way into position. To-morrow, doubtless, the grand battle will be fought, when I trust the good Lord will grant us a glorious victory, and one that will make glad the hearts of all loyal people on New-Year's Day.

I saw Lieutenant-Colonel Given, Eighteenth Ohio. Twelve of his men had been wounded. Met Colonel Wagner, Fifteenth Indiana. Starkweather's brigade lost its wagon train this forenoon. Jeff C. Davis, I am told, was wounded this evening. A shell exploded near a group, consisting of General Rosecrans and staff, killing two horses and wounding two men.

31. At six o'clock in the morning my brigade marches to the front and forms in line of battle. The roar of musketry and artillery is incessant. At nine o'clock we move into the cedar woods on the right to support McCook, who is reported to be giving way. General Rousseau points me to the place he desires me to defend, and enjoins me to "hold it until hell freezes over," at the same time telling me that he may be found immediately on the left of my brigade with Loomis' battery. I take position. An open wood is in my front; but where the line is formed, and to the right and left, the cedar thicket is so dense as to render it impossible to see the length of a regiment. The enemy comes up directly, and the fight begins. The roar of the guns to the right, left, and front of my brigade sounds like the continuous pounding on a thousand anvils. My men are favorably situated, being concealed by the cedars, while the enemy, advancing through the open woods, is fully exposed. Early in the action Colonel Foreman, of the Fifteenth Kentucky, is killed, and his regiment retires in disorder. The Third Ohio, Eighty-eighth, and Forty-second Indiana, hold the position, and deliver their fire so effectively that the enemy is finally forced back. I find a Michigan regiment and attach it to my command, and send a staff officer to General Rousseau to report progress; but before he has time to return, the enemy makes another and more furious assault upon my line. After a fierce struggle, lasting from forty to sixty minutes, we succeed in repelling this also. I send again to General Rousseau, and am soon after informed that neither he nor Loomis' battery can be found. Troops are reported to be falling back hastily, and in disorder, on my left. I send a staff officer to the right, and ascertain that Scribner's and Shepperd's brigades are gone. I conclude that the contingency has arisen to which General Rousseau referred—that is to say, that hell has frozen over—and about face my brigade and march to the rear, where the guns appear to be hammering away with redoubled fury. In the edge of the woods, and not far from the Murfreesboro pike, I find the new line of battle, and take position. Five minutes after the enemy strike us. For a time—I can not even guess how long—the line stands bravely to the work; but the regiments on our left get into disorder, and finally become panic-stricken. The fright spreads, and my brigade sweeps by me to the open field in our rear. I hasten to the colors, stop them, and endeavor to rally the men. The field is by this time covered with flying troops, and the enemy's fire is most deadly. My brigade, however, begins to steady itself on the colors, when my horse is shot under me, and I fall heavily to the ground. Before I have time to recover my feet, my troops, with thousands of others, sweep in disorder to the rear, and I am left standing alone. Going back to the railroad, I find my men, General Rousseau, Loomis, and, in fact, the larger part of the army. The artillery has been concentrated at this point, and now opens upon the advancing columns of the enemy with fearful effect, and continues its thunders until nightfall. The artillery saved the army. The battle during the whole day was terrific.

I find that soon after the fight began in the cedars, our division was ordered back to a new line, and that the order had been delivered to Scribner and Shepperd, but not to me. They had, consequently, retired to the second position under fire, and had suffered most terribly in the operation; while my brigade, being forgotten by the division commander, or by the officer whose duty it was to convey the order, had held its ground until it had twice repulsed the enemy, and then changed position in comparative safety. A retrograde movement under fire must necessarily be extremely hazardous. It demoralizes your own men, who can not, at the moment, understand the purpose of the movement, while it encourages the enemy. The one accepts it as an indication of defeat; the other as an assurance of victory.

McCook had been surprised and shattered in the morning. This unexpected success had inspired the rebels and dispirited us. They fought like devils, and the victory—if victory there was to either army—belonged to them.

When the sun went down, and the firing ceased, the Union army, despondent, but not despairing, weary and hungry, but still hopeful, lay on its arms, ready to renew the conflict on the morrow.