The Second and Third Brigades of my division had been placed toward the left of the line previous to my arrival, but at what point I was unable to ascertain.

I directed the First Brigade, under the immediate command of General Naglee, to proceed as directed by the commanding general.

The Second and Third Brigades, as will be seen by the inclosed reports of their commandants, did good service on the left, and I have good reason to believe that the opportune arrival of the First Brigade saved General Hancock from a probable severe disaster.

The officers and men of the division behaved in a very creditable manner, and I know from personal observation that the First Brigade,under General Naglee, was formed as a sustaining force in a prompt and skillful manner. The staff officers of my division performed their duty as promptly and satisfactorily.

I am, very respectfully, your obedient servant,

SILAS CASEY,

Brigadier General, Commanding Third Division, Fourth Army Corps.

Captain C. C. SUYDAM,

Assistant Adjutant-General, Fourth Army Corps.

No. 57. Report of Brigadier General Henry M. Naglee,

U. S. Army, commanding First Brigade.

CAMP NEAR WILLIAMSBURG, VA.,

Headquarters First Brigade, Casey's Division, May 7, 1862.

CAPTAIN: I have the honor to report that, in pursuance of orders from General Keyes and General Casey (A, B, and C, attached), the brigades herein referred to were in motion by 9 o'clock a.m. on Sunday, the 4th instant, and were by 10.30 a.m. in occupation of the formidable works at Lee's Mill, which had been evacuated on Friday night, May 2, as reported by men. All of the surrounding country was covered with heavy fallen timber, and in the roads were buried torpedoes, which were not discovered until an explosion of one of them killed 1 and wounded 6 others of Colonel Dodge's Fifty-second Pennsylvania Volunteers.

At 1 p.m. Colonel Adams (Graham's brigade), Major Whittlesey's Fifth Cavalry, and Colonel Bailey's four New York batteries joined the column, and shortly afterward Captain Suydam, assistant adjutant-general to General Keyes, permitted a copy of a portion of a map of the immediate vicinity of Lee's Mill to be taken, and reiterated the orders above referred to.

Colonel Davis, with the One hundred and fourth Pennsylvania, with one section of Captain Regan's battery, reconnoitered the country toward Grove's wharf, and found none of the enemy. With the remainder of the force we proceeded, with the caution recommended by General Casey, in the direction of the Half-way House. We passed through the various and many field works 3 miles from Lee's Mill, and without any hinderance continued until we came into the main road leading from Yorktown to Williamsburg, where, when within 2 miles of the Half-way House, at 2 p.m., my advance guard had met Governor Sprague, who informed us of the position of affairs near Williamsburg, and that it was absolutely