HEADQUARTERS SEVENTH ARMY CORPS, Fort Monroe, Va., August 11, 1862.

Major General GEORGE B. McCLELLAN,
Commanding Department of Virginia:

GENERAL: I have just received the communication of General Williams in regard to the flag of truce sent from here to City Point last week, and I regret exceedingly that the failure to report should have been regarded as a want of courtesy to you as the general commanding or as a violation of military rule. Before I took command at this post and ever since a steamer has been sent to City Point, with more or less regularity as to time, to convey letters for our prisoners in the insurgent States, to receive letters for theirs, and to land persons ordered to be sent through our lines by the Secretary of War. Of this practice I supposed you were aware. The instructions have always been the same, to deliver the letters and the persons sent under the protection of the flag, and return immediately to this post.

The flag sent last week was for these purposes and with the usual instructions. As the steamer was about leaving some ten or twelve released prisoners arrived here from Baltimore, with instructions from the War Department to deliver them for exchange. Thinking it a favorable opportunity to get them off our hands I sent them to City Point, and took a receipt, which has been delivered to General Thomas to-day.

When you were on the Chickahominy it would not have been practicable for the officer in charge of the flag to report, and since the change of position to the James River the old routine has been continued without adverting to the altered circumstances. If, therefore, there is a fault, it is entirely my own and not that of the officer; and it has arisen from my construction of the obligation which a flag of truce imposes on those who use it. I supposed it to be my duty to send the vessel bearing it to her destination and then to order her back to the point of departure, without stopping anywhere for any purpose, but confining her rigidly both in going and returning to the specific purpose for which she was sent.

With this view of the sacred character of the flag of truce, when I went to meet General Hill and desired to see you on my way I did not raise the flag until after I had passed your headquarters and took it down the moment I reached them on my return. If I am in error it is the result of too strict a construction of my duty, and I regret that it should have been considered as a departure, even through inadvertence, from the rules of military subordination or courtesy.

It is hardly necessary for me to add that no flag will be sent from this post hereafter without instructions from you. When persons arrive here with orders from the War Department to be sent across the lines I will retain them and advise you.

I am, very respectfully, your obedient servant,

JOHN A. DIX,

Major-General.

HARRISON'S LANDING, August 11, 1862.

M. C. MEIGS,

Quartermaster-General:

We are embarking a cavalry regiment of 1,000 men and horses. It will require three days for the medical department to ship away the