On the 2nd instant, at Morristown, I met a party of the enemy, about 110 strong, under command of Major Arnold. I immediately engaged them, and after a short fight they retired with a loss of 1 officer mortally wounded, so that he died two days afterward, and 5 men wounded, who succeeded in getting away. I feared that this early discovery of our movement would prevent its successful execution unless this party could be cut off in some way. Therefore, learning at Russellville that they had taken the Bull's Gap road, I detached Major Smith, with four companies, to get in their rear beyond Bull's Gap, but much to my surprise they did not stop, but took the Snapp's Ferry road, leading toward Kingsport. Failing to cut them off, I encamped for the night at Blue Springs and went the next morning to Greeneville. Here, from the best information that I could get, I learned that there were from 250 to 300 of the enemy at Johnson's Depot, seven miles beyond Jonesborough, where the headquarters of Vaughn's brigade had been established; about 50 at Carter's Station; about 100 at Zollicoffer; Morgan's headquarters at Bristol, while there were many scattering bands of scouts through the country. The whole number of armed men WEST of Bristol was estimated at not over 1,000. When at Russellville I heard that there was a party of about 150 at Rogersville, which afterward proved true, though I did not credit the report at that time. That party passed through Bull's Gap on Wednesday, the 3rd instant. In view of all these facts I did not deem it prudent to proceed farther than Greeneville. The enemy could easily concentrate a force which, with the aid of their works at the bridges, would give me great trouble, and an attempt and failure would be worse than a withdrawal. I therefore returned from Greeneville on the 3rd instant, and arrived safely in camp last evening. While I was very loath to abandon the expedition, it seemed to rudence. If it shall be desired to renew the undertaking I shall be glad to do it at any time and with any force which the general commanding may think best.

Very respectfully, your obedient servant,

L. S. TROWBRIDGE,

Lieutenant-Colonel, Commanding.

Lieutenant E. W. S. NEFF,

Aide-de-Camp and Acting Assistant Adjutant-General.

AUGUST 1-30, 1864. - Expedition from La Grange, Tenn., to Oxford, Miss.

SUMMARY OF THE PRINCIPAL EVENTS.

August 7-9, 1864. - Skirmishes at the Tallahatchie River, Miss.

9, 1864. - Skirmishes at Hurricane Creek, Miss.

Skirmishes at Oxford, Miss.

10, 1864. - Skirmish at the Tallahatchie River, Miss.

13-14, 1864. - Skirmishes at Hurricane Creek, Miss.

14, 1864. - Skirmish at Lamar, Miss.

19, 1864. - Skirmish at Hurricane Creek, Miss.

23, 1864. - Skirmish at Abbeville, Miss.

REPORTS, ETC.

Numbers 1. - Itinerary of the First DIVISION, SIXTEENTH Army Corps, commanded by Brigadier General Joseph A. Mower, U. S. Army.

Numbers 2. - Colonel De Witt C. Thomas, Ninety-THIRD Indiana Infantry, First Brigade.

Numbers 3. - Colonel Lucius F. Hubbard, Fifth Minnesota Infantry, commanding Second Brigade.