On the 8th of March, 1862, the President directed, by the following order, the organization of the active portion of the Army of the Potomac into four army corps, and the formation of a fifth corps from the divisions of Banks and Shields.

The following is the text of the President's order:

PRESIDENT'S GENERAL WAR ORDER,

No. 2.

EXECUTIVE MANSION,
Washington, March 8, 1862.

Ordered, 1. That the major-general commanding the Army of the Potomac proceed forthwith to organize that part of the said army destined to enter upon active operations (including the reserve, but excluding the troops to be left in the fortifications about Washington) into four army corps, to be commanded according to seniority of rank, as follows:

First Corps to consist of four divisions, and to be commanded by Maj. Gen. I. McDowell.

Second Corps to consist of three divisions, and to be commanded by Brig. Gen. E. V. Sumner.

Third Corps to consist of three divisions, and to be commanded by Brig. Gen. S. P. Heintzelman.

Fourth Corps to consist of three divisions, and to be commanded by Brig. Gen. E. D. Keyes.

2. That the divisions now commanded by the officers above assigned to the commands of army corps shall be embraced in and form part of their respective corps.

3. The forces left for the defense of Washington will be placed in command of Brig. Gen. James S. Wadsworth, who shall also be military governor of the District of Columbia.

4. That this order be executed with such promptness and dispatch as not to delay the commencement of the operations already directed to be undertaken by the Army of the Potomac.

5. A fifth army corps, to be commanded by Maj. Gen. N. P. Banks, will be formed from his own and General Shields' (late General Lander's) divisions.

ABRAHAM LINCOLN.

The following order, which was made as soon as circumstances permitted, exhibits the steps taken to carry out the requirements of the President's War Order, No. 2:

GENERAL ORDERS,

HEADQUARTERS ARMY OF THE POTOMAC,
Fairfax Court-House, Va., March 13, 1862.

In compliance with the President's War Order, No. 2, of March 8, 1862, the active portion of the Army of the Potomac is formed into army corps, as follows:

First Corps, Maj. Gen. Irvin McDowell, to consist for the present of the divisions of Franklin, McCall, and King.

Second Corps, Brig. Gen. E. V. Sumner; divisions, Richardson, Blenker, and Sedgwick.

Third Corps, Brig. Gen. S. P. Heintzelman; divisions, F. J. Porter, Hooker, and Hamilton.

Sub

Fourth Corps, Brig. Gen. E. D. Keyes; divisions, Couch, Smith, and Casey. Fifth Corps, Maj. Gen. N. P. Banks; divisions, Williams and Shields. The cavalry regiments attached to divisions will for the present remain so. sequent orders will provide for these regiments, as well as for the reserve artillery, regular infantry, and regular cavalry. Arrangements will be made to unite the divisions of each army corps as promptly as possible.

The commanders of divisions will at once report in person, or, where that is impossible, by letter to the commander of their army corps. By command of Major-General McClellan :

A. V. COLBURN, Assistant Adjutant-General.

I add a statement of the organization and composition of the troops on April 1, commencing with the portion of the Army of the Potomac which went to the Peninsula, giving afterwards the regiments and batteries left on the Potomac and in Maryland and Virginia after April 1, 1862:

Troops of the Army of the Potomac sent to the Peninsula in March and early in April, 1862.

1st. Cavalry reserve, Brig. Gen. P. St. G. Cooke.-Emory's brigade: Fifth U. S. Cavalry; Sixth U. S. Cavalry; Sixth Pennsylvania Cavalry. Blake's brigade: First U. S. Cavalry; Eighth Pennsylvania Cavalry; Barker's squadron Illinois cavalry. 2d. Artillery reserve, Col. Henry J. Hunt: Graham's battery (K and G), First U. S., six Napoleon guns; Randol's battery (E), First U. S., six Napoleon guns; Carlisle's battery (E), Second U. S., six 20-pounder Parrott guns; Robertson's battery, Second U. S., six 3-inch ordnance guns; Benson's battery (M), Second U. S., six 3-inch ordnance guns; Tidball's battery (A), Second U. S., six 3-inch ordnance guns; Edwards' battery (L and M), Third U..S., six 10-pounder Parrott guns; Gibson's battery (C and G), Third U. S., six 3-inch ordnance guns; Livingston's battery (F and K), Third U. S., four 10-pounder Parrott guns; Howe's battery (G), Fourth U. Š., six Napoleon guns; De Russy's battery (K), Fourth U. S., six Napoleon guns; Weed's battery (I), Fifth Ú. S., six 3-inch ordnance guns; Smead's battery (K), Fifth U. S, four Napoleon guns; Ames' battery (A), Fifth U. S., six (four 10-pounder Parrott and two Napoleon) guns; Diedrich's battery (A), New York artillery battalion, six 20-pounder Parrott guns; Voegelie's battery (B), New York artillery battalion, four 20-pounder Parrott guns; Knieriem's battery (C), New York artillery battalion, four 20-pounder Parrott guns; Grim's battery (D), New York artillery battalion, six 32-pounder howitzer guns; total, 100 guns.

3d. Volunteer engineer troops, General Woodbury: Fifteenth New York Volunteers, Fiftieth New York Volunteers. Regular engineer troops, Captain Duane: Companies A, B, and C, U. S. Engineers. Artillery troops, with siege trains: First Connecticut Heavy Artillery, Colonel Tyler.

4th. Infantry reserve (regular brigade), General Sykes: Nine companies Second U. S. Infantry, seven companies Third U. S. Infantry, ten companies Fourth U. S. Infantry, ten companies Sixth U. S. Infantry, eight companies Tenth and Seventeenth U. S. Infantry, six companies Eleventh U. S. Infantry, eight companies Twelfth U. S. Infantry, nine companies Fourteenth U. S. Infantry, and Fifth New York Volunteers, Colonel Warren.

SECOND CORPS, GENERAL sumner.

Cavalry.-Eighth Illinois Cavalry, Colonel Farnsworth, and one squadron Sixth New York Cavalry. RICHARDSON'S DIVISION.

Artillery.-Clarke's battery (A and C), Fourth U. S., six Napoleon guns; Frank's battery (G), First New York, six 10-pounder Parrott guns; Pettit's battery (B), First New York, six 10-pounder Parrott guns; Hogan's battery (A), Second New York, six 10-pounder Parrott guns.

Infantry.-Howard's brigade: Fifth New Hampshire, Eighty-first Pennsylvania, and Sixty-first and Sixty-fourth New York Volunteers. Meagher's brigade: Sixtyninth, Sixty-third, and Eighty-eighth New York Volunteers. French's brigade: Fifty-second, Fifty-seventh, and Sixty-sixth New York and Fifty-third Pennsylvania Volunteers.

SEDGWICK'S DIVISION.

Artillery.-Kirby's battery (I), First U. S., six Napoleon guns; Tompkins' battery (A), First Rhode Island, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Bartlett's battery (B), First Rhode Island, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Owen's battery (G), six 3-inch ordnance guns.

Infantry.-Gorman's brigade: Second New York State Militia, Fifteenth Massachusetts, Thirty-fourth New York, and First Minnesota Volunteers. Burns' brigade: Sixty-ninth, Seventy-first, Seventy-second, and One hundred and sixth Pennsylvania Volunteers. Dana's brigade: Nineteenth and Twentieth Massachusetts, Seventh Michigan, and Forty-second New York Volunteers.

NOTE.-Blenker's division detached, and assigned to the Mountain Department.

THIRD CORPS, GENERAL HEINTZELMAN.

Cavalry.—Third Pennsylvania Cavalry, Colonel Averell.

PORTER'S DIVISION.

Artillery.-Griffin's battery (D), Fifth U. S., six 10-pounder Parrott guns; Weeden's battery (C), Rhode Island; Martin's battery (C), Massachusetts, six Napoleon guns; Allen's battery (E), Massachusetts, six 3-inch ordnance guns.

Infantry.-Martindale's brigade: Second Maine, Eighteenth and Twenty-second Massachusetts, and Twenty-fifth and Thirteenth New York Volunteers. Morell's brigade: Fourteenth New York, Fourth Michigan, Ninth Massachusetts, and Sixty-second Pennsylvania Volunteers. Butterfield's brigade: Seventeenth, Forty-fourth, and Twelfth New York, Eighty-third Pennsylvania, and Stockton's [Sixteenth] Michigan Volunteers.

First Berdan Sharpshooters.

HOOKER'S DIVISION.

Artillery. -Hall's battery (H), First U. S., six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Smith's battery, Fourth New York, six 10-pounder Parrott guns; Bramhall's battery, Sixth New York, six 3-inch ordnance guns; Osborn's battery (D), First New York Artillery, four 3-inch ordnance guns.

Infantry.-Sickles' brigade: First, Second, Third, Fourth, and Fifth Excelsior, New York. Naglee's brigade: First and Eleventh Massachusetts, Twenty-sixth Pennsylvania, and Second New Hampshire Volunteers. Colonel Starr's brigade: Fifth, Sixth, Seventh, and Eighth New Jersey Volunteers.

HAMILTON'S DIVISION.

Artillery.-Thompson's battery (G), Second U. S., six Napoleon guns; Beam's battery (B), New Jersey, six (four 10-pounder Parrott and two Napoleon) guns; Randolph's battery (E), Rhode Island, six (four 10-pounder Parrott and two Napoleon) guns.

Infantry.-Jameson's brigade: One hundred and fifth, Sixty-third, and Fiftyseventh Pennsylvania and Eighty-seventh New York Volunteers. Birney's brigade: Thirty-eighth and Fortieth New York and Third and Fourth Maine Volunteers. brigade: Second, Third, and Fifth Michigan and Thirty-seventh New York Volun

teers.

FOURTH CORPS, GENERAL KEYES.

COUCH'S DIVISION,

Artillery.-McCarthy's battery (C), First Pennsylvania, four 10-pounder Parrott guns; Flood's battery (D), First Pennsylvania, four 10-pounder Parrott guns; Miller's battery (E), First Pennsylvania, four Napoleon guns; Brady's battery (F), First Pennsylvania, four 10-pounder Parrott guns.

Infantry.-Graham's brigade: Sixty-seventh (First Long Island) and Sixty-fifth (First U. S. Chasseurs) New York, and Twenty-third, Thirty-first, and Sixty-first Pennsylvania Volunteers. Peck's brigade: Ninety-eighth, One hundred and second, and Ninety-third Pennsylvania, and Sixty-second and Fifty-fifth New York Volunteers. brigade: Second Rhode Island, Seventh and Tenth Massachusetts, and Thirtysixth New York Volunteers.

SMITH'S DIVISION.

Artillery.-Ayres' battery (F), Fifth U. S., six (four 10-pounder Parrott and two Napoleon) guns; Mott's battery, Third New York, six (four 10-pounder Parrott and two Napoleon) guns; Wheeler's battery (E), First New York, four 3-inch ordnance guns; Kennedy's battery, First New York, six 3-inch ordnance guns.

Infantry.-Hancock's brigade: Fifth Wisconsin, Forty-ninth Pennsylvania, fortythird New York, and Sixth Maine Volunteers. Brooks' brigade: Second, Third, Fourth, Fifth, and Sixth Vermont Volunteers. Davidson's brigade: Thirty-third, Seventy-seventh, and Forty-ninth New York and Seventh Maine Volunteers.

CASEY'S DIVISION.

Artillery.-Regan's battery, Seventh New York, six 3-inch ordnance guns: Fitch's battery, Eighth New York, six 3-inch ordnance guns; Bates' battery (A), First New York, six Napoleon guns; Spratt's battery (H), First New York, four 3-inch ordnance guns.

Infantry.-Keim's brigade: Eighty-fifth, One hundred and first, and One hundred and third Pennsylvania and Ninety-sixth New York Volunteers. Palmer's brigade: Eighty-fifth, Ninety-eighth, Ninety-second, Eighty-first, and Ninety-third New York Volunteers. brigade: One hundred and fourth and Fifty-second Pennsylvania, Fifty-sixth and One hundredth New York, and Eleventh Maine Volunteers.

5th. Provost guard: Second U. S. Cavalry; battalions Eighth and Seventeenth U. S. Infantry.

At general headquarters: Two companies Fourth U. S. cavalry, one company Onedia cavalry (New York volunteers), and one company Sturges' rifles (Illinois volunteers).

The following troops of the Army of the Potomac were left behind or detached on and in front of the Potomac for the defense of that line April 1, 1862. Franklin's and McCall's divisions, at subsequent and different dates, joined the active portion of the army on the Peninsula. Two brigades of Shields' division joined at Harrison's Landing:

FIRST CORPS, GENERAL MCDOWELL.

Cavalry. First, Second, and Fourth New York, and First Pennsylvania.
Sharpshooters.-Second Regiment Berdan Sharpshooters.

FRANKLIN'S DIVISION.

Artillery.-Platt's battery (D), Second U. S., six Napoleon guns; Porter's battery (A), Massachusetts, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Hexamer's battery (A), New Jersey, six (four 10-pounder Parrott and two 12-pounder howitzer) guns; Wilson's battery (F), First New York Artillery, four 3-inch ordnance guns.

Infantry.-Kearny's brigade: First, Second, Third, and Fourth New Jersey Volunteers. Slocum's brigade: Sixteenth and Twenty-seventh New York, Fifth Maine, and Ninety-sixth Pennsylvania Volunteers. Newton's brigade: Eighteenth, Thirty-first, and Thirty-second New York, and Ninety-fifth Pennsylvania Volunteers.

M'CALL'S DIVISION.

Artillery.-Seymour's battery (C), Fifth U. S., six Napoleon guns; Easton's battery (A), First Pennsylvania, four Napoleon guns; Cooper's battery (B), First Pennsylvania, six 10-pounder Parrott guns; Kerns' battery (G), First Pennsylvania, six (two 10-pounder and four 12-pounder) Parrott guns.

Infantry.-Reynolds' brigade: First, Second, Fifth, and Eighth Pennsylvania Reserve Regiments. Meade's brigade: Third, Fourth, Seventh, and Eleventh Pennsylvania Reserve Regiments. Ord's brigade: Sixth, Ninth, Tenth, and Twelfth Pennsylvania Reserve Regiments. First Pennsylvania Reserve Rifles.

KING'S DIVISION.

Artillery.-Gibbon's battery (B), Fourth U. S., six Napoleon guns; Monroe's battery (D), First Rhode Island, six 10-pounder Parrott guns; Gerrish's battery (A), New Hampshire, six Napoleon guns; Durell's battery, Pennsylvania, six 10-pounder Parrott guns.

Infantry.

brigade: Second, Sixth, and Seventh Wisconsin, and Nineteenth Indiana Volunteers. Patrick's brigade: Twentieth, Twenty-first, Twenty-Third, and Twenty-fifth New York State Militia. Augur's brigade: Fourteenth New York State Militia [Eighty-fourth Volunteers], and Twenty-second, Twenty-fourth, and Thirtieth New York Volunteers.

FIFTH CORPS, GENERAL BANKS.

Cavalry. First Maine, First Vermont, First Michigan, First Rhode Island, Fifth and Eighth New York, Keys' battalion of Pennsylvania, eighteen companies of Maryland, one squadron of Virginia.

Unattached. Twenty-eighth Pennsylvania Volunteers and Fourth Regiment Potomac Home Brigade (Maryland Volunteers).

WILLIAMS' DIVISION.

Artillery.-Best's battery (F), Fourth U. S., six Napoleon guns; Hampton's battery, Maryland, four 10-pounder Parrott guns; Thompson's battery, Maryland, four 10-pounder Parrott guns; Matthews' battery (F), Pennsylvania, six 3-inch ordnance guns; Cothran's battery (M), First New York, six 10-pounder Parrott guns; Knap's battery, Pennsylvania, six 10-pounder Parrott guns; McMahon's battery, New York, six 3-inch ordnance guns.

Infantry.-Abercrombie's brigade: Twelfth and Second Massachusetts, and Sixteenth Indiana, First Potomac Home Brigade (Maryland), one company Zouaves d'Afrique (Pennsylvania) Volunteers. brigade: Ninth New York State Militia, [Eighty-third Volunteers], and Twenty-ninth Pennsylvania, Twenty-seventh Indiana, and Third Wisconsin Volunteers. brigade: Twenty-eighth New York, Fifth Connecticut, Forty-sixth Pennsylvania, First Maryland, Twelfth Indiana, and Thirteenth Massachusetts Volunteers.

SHIELDS' DIVISION.

Artillery.-Clark's battery (E), Fourth U. S., six 10-pounder Parrott guns; Jenks' battery (A), First Virginia, four 10-pounder Parrott and two 6-pounder guns; Davey's battery (B), First Virginia, two 10-pounder Parrott guns; Huntington's battery (A), First Ohio, six 13-pounder James guns; Robinson's battery (L), First Ohio, two 12-pounder howitzers and four 6-pounder guns, and battery, Fourth Ohio Artillery. Infantry.- brigade: Fourteenth Indiana, Fourth, Eighth, and Sixty-seventh Ohio, Seventh Virginia, and Eighty-fourth Pennsylvania Volunteers. - brigade: Fifth, Sixty-second, and Sixty-sixth Ohio, Thirteenth Indiana, and Thirty-ninth Illinois Volunteers. brigade: Seventh and Twenty-ninth Ohio, Seventh Indiana, First Virginia, and One hundred and tenth Pennsylvania Volunteers. Andrew S. S.

GENERAL WADSWORTH'S COMMAND.

Cavalry.-First New Jersey Cavalry at Alexandria, and Fourth Pennsylvania Cavalry east of the Capitol.

Artillery and Infantry.-Tenth New Jersey Volunteers, Bladensburg road; One hundred and fourth New York Volunteers, Kalorama Heights; First Wisconsin Heavy Artillery, Fort Cass, Virginia; three batteries of New York artillery, Forts Ethan Allen and Marcy; depot of New York Light Artillery, Camp Barry; Second District of Columbia Volunteers, Washington City; Twenty-sixth Pennsylvania Volunteers, G-street wharf; Twenty-sixth New York Volunteers, Fort Lyon; Ninety-fifth New York Volunteers, Camp Thomas; Ninety-fourth New York and detachment of Eighty-eighth Pennsylvania Volunteers, Alexandria; Ninety-first Pennsylvania Volunteers, Franklin Square Barracks; Fourth New York Artillery, Forts Carroll and Greble; One hundred and twelfth Pennsylvania Volunteers, Fort Saratoga; Seventy-sixth New York Volunteers, Fort Massachusetts; Fifty-ninth New York Volunteers, Fort Pennsylvania; detachment of Eighty-eighth Pennsylvania Volunteers, Fort Good Hope; Ninety-ninth Pennsylvania Volunteers, Fort Mahon; Second New York Light Artillery, Forts Ward, Worth, and Blenker; One hundred and seventh and Fiftyfourth Pennsylvania Volunteers, Kendall Green; Dickenson's Light Artillery, Eightysixth New York, and detachment of Eighty-eighth Pennsylvania Volunteers, east of the Capitol; Fourteenth Massachusetts (Volunteers) Heavy Artillery and Fifty-sixth Pennsylvania Volunteers, Forts Albany, Tillinghast, Richardson, Runyon, Jackson, Barnard, Craig, and Scott; detachments of Fourth U. S. Artillery and Thirty-seventh New York Volunteers, Fort Washington; Ninety-seventh, One hundred and first, and Ninety-first New York, and Twelfth Virginia Volunteers, Fort Corcoran.

In camp near Washington.-Sixth and Tenth New York, Swain's New York, and Second Pennsylvania Cavalry, all dismounted.

These troops (3,359 men) were ordered to report to Colonel Miles, commanding the railroad guard, to relieve 3,306 older troops ordered to be sent to Manassas to report to General Abercrombie.

GENERAL DIX'S COMMAND, BALTIMORE.

Cavalry.-First Maryland Cavalry and detachment of Purnell Legion Cavalry. Artillery.-Battery I, Second U. S.; battery, Maryland; battery L, First New York, and two independent batteries of Pennsylvania artillery.

Infantry.-Third, and Fourth New York, Eleventh, Eighty-seventh, and One hundred and eleventh Pennsylvania, detachment Twenty-first Massachusetts, Second Delaware, Second Maryland, First and Second Eastern Shore (Maryland) Home Guards, and Purnell Legion (two battalions) Maryland Volunteers.

In a staff charged with labors so various and important as that of the Army of the Potomac, a chief was indispensable to supervise the various departments and to relieve the commanding general of details. The office of chief of staff, well known in European armies, had not