Brigadier General S. WILLIAMS,

Assistant Adjutant-General, Army of the Potomac:

GENERAL: The preceding order has been sent to Colonel Murphy, who last evening encamped with his command about 3 miles out from here on the Fredericksburg road.

Very respectfully, yours, &c.,

JNO. A. RAWLINS,

Brigadier-General and Chief of Staff.

FREDERICKSBURG, May 17, 1864.

(Received 2.40 p.m.)

Honorable E. M. STANTON,

Secretary of War:

General Grant desires the immediate repairs of the railroad from Aquia Creek to Hamilton's Crossing. I have instructed the chief of the Military Railroad Office, and sent orders to the construction force now at Belle Plain. A second bridge is much needed here. General Benham should have twenty more pontoons sent to him at once. There are teams at Belle Plain to haul his bridge materials to this place. Your dispatches of yesterday received here at 4.30 a.m. I expect to go to Belle Plain this afternoon. I have ordered more wagons and ambulances to Belle Plain for service between that place and this. There are many badly wounded here, for whose transportation the opening of the Rappahannock is very desirable. About 600 wounded were rescued yesterday by a close movement from Fifth and Second Corps Hospitals, within the enemy's lines, and have arrived here in generally good condition. They were kindly treated by the enemy. There is little doubt of Mayor Slaughter's guilt. If in town he is concealed. The attempt to arrest him will be made.

M. C. MEIGS,

Quartermaster-General.

BELLE PLAIN, May 17, 1864-7 p.m.

(Received 7.20 p.m.)

SECRETARY OF WAR:

Your dispatches reached me at Fredericksburg at 4.30 a.m. to-day. I have given orders for such arrangements for comfort and quick transportation of wounded and for their supply as seemed advisable and practicable. I wrote to General Grant in regard to the situation of the place. Directed General Benham to construct another pontoon bridge at Fredericksburg. I came to this place his afternoon; visited the prisoners' camp, which is sufficiently guarded. Over 3,000 are shipped to-day, leaving only about 2,500 in the camp. The guard is about 1,100 strong-two regiments. The wharves and arrangements here for embarking prisoners and wounded, and for receiving supplies are sufficient. The work is well and quickly done. The construction corps is at Aquia Creek, already at work on the railroad. Three of the parties implicated with Mayor Slaughter are in arrest. An effort will be made to catch him to-night. They will be sent to Washington in close arrest; the mayor in irons, if caught. Straw for bedding and soft bread for the diet of the wounded are