July 21.- All cavalry in the Department of Virginia except two regiments, all in the Department of North Carolina except one regiment, and all in the Middle Department except one regiment.

August 1.- All white troops, infantry, cavalry, and artillery, in the Department of Texas, which, in the judgment of Major-General Sheridan, could be dispensed with.

August 3.- The same order was extended to the Department of Louisiana.

August 14.- Additional infantry and heavy artillery (white) in military departments as follows: Virginia, 5,000; North Carolina, 8,000; Washington, 8,000; Mississippi, 2,000; Kentucky, 5,000; Middle, 6,000.

August 21.- Three thousand additional white troops in the Department of Arkansas.

September 8.- All surplus troops in the Department of Washington, so as to reduce that command to 6,000 officers and men of all arms. September 8.- All organizations of colored troops which were enlisted in Northern States.

October 9.- All the remaining forces (white) of the cavalry arm east of the Mississippi.

October 9.;- All troops on the Pacific Coast, as many as possible immediately; the remainder on the arrival of the last battalion of the Fourteenth U. S. Infantry.

October 10.- All troops in New Mexico; one regiment immediately, the remainder on the arrival of certain regular troops.

In addition to the foregoing, and from time to time as the services of the troops could be dispensed with, sixty-eight regiments, seven companies, and six battalions were ordered mustered out.

The rapidity with which the work has been executed will be apparent from the fact that to August 7, 640,806 troops had been mustered out; August 22, 719,338; September 14, 741,107; October 15, 785,205; November 15, 800,963.

The command of Major-General Sherman (Army of the Tennessee and Army of the Georgia) and the Army of the Potomac were first to complete their musters out entirely. Regiments commenced leaving General Sherman's command, then numbering, present and absent, 116, 183 officers and men, from the rendezvous near Washington on the 29th of May, and on the 1st of August the last one of the regiments mustered out left Louisville, Ky., to which point the command (after the musters out left therefrom were partly completed) was transferred, and the armies composing it merged into one, called the Army of the Tennessee. The work of mustering out the troops was not continuous, it having been interrupted and delayed by the transfer of the two armies from this city to Louisville and their subsequent consolidation.

Regiments commenced leaving the Army of the Potomac (when numbering, including Ninth Corps, 162,851 officers and men, present and absent) from the rendezvous near this city on the 29th of May, and about six weeks thereafter (July 19) the last regiment started for home. During the interval the work, like that from General Sherman's command, was not continuous, it being interrupted and delayed by the movement of the Sixth Corps from Danville, Va., to Washington, and the consolidation, by orders of June 28, of the remaining absent, 22,699 officers and men.