HDQRS. ARTILLERY BRIGADE, NINTH ARMY CORPS, December 17, 1864.

Brevet Major-General HUNT,
Chief of Artillery, Army of the Potomac:

Enemy opened fire from one 8-inch gun from front of Fort Sedgwick, and two mortars in front of Fort Morton. A few shots were returned from our batteries.

JNO. C. DIDBALL,

Brevet Brigadier-General.

HEADQUARTERS SECOND CAVALRY DIVISION, December 17, 1864.

Brigadier General S. WILLIAMS,
Assistant Adjutant-General, Army of the Potomac:

GENERAL: The cavalry picket-line is established as directed. The left of the line of the Fifth Army Corps, with which I am required to connect, rests on the road leading from McCann's to Lee's Mill. The right of the cavalry line rests on Warwick Swamp, between this road and the plank road. Beginning at Warwick Swamp the line passes Davenport Church, crosses the Norfolk railroad at Baxeter's, thence follows the City Point road to Mount Singai Church, thence bears to the east and crosses the stage road near Green's, crosses the telegraph road at Bland's, and terminates at Bailey's Creek. There are strong reserves on the McCann's and Lee's Mill road, in rear of Davenport Church, on the road west of the Norfolk railroad, on the Quaker road, in rear of Mount Sinai Church, on the stage and telegraph roads, and at Prince George Court-House. The lines is continuously covered by pickets, and is properly supported by reserves. Scouting parties are daily sent in front of the lines. It is possible that an occasional scout or guerrilla may be occasionally found within our lines. This cannot well be prevented in a densely wooded country, which mounted men cannot traverse in all directions. As regard the report of Captain Philip Schuyler, Fourteenth Infantry, in charge of the provost-marshal-general's office, concerning the unsafely of a portion of the country within our lines, I would report that from the locality defined as that on which his party was attacked by five dismounted guerrillas I infer they were outside the cavalry line. A party of ten dismounted men, having only pistols, escorting three wagons, cannot expect to go out beyond our lines and be unmolested by the enemy, and an officer who would order such a foray is exceedingly culpable. A brigade of cavalry at Prince George Court-House would facilitate the picketing of the country toward the James River, as the details for picket duty would have much less distance to march. Prince George Court-House is in rear of the center of the cavalry picket-line, and is in all respects a good position for the entire division, save its comparative remoteness from the railroad, and the increased distance which would have to be traveled to reach the left of the main line of our army. I send a staff officer who will point out on a map the position of the cavalry picket-line and reserves.

Very respectfully, your obedient servant,

D. McM. GREGG,

Bvt. Major General, U. S. Vols., Commanding Second Cavalry Division.