Report of Lieutenant Colonel Gilbert Riordan,Thirty-Seventh New York Infantry.

Camp on the Field,

May 4, 1863.

Major: I have the honor to forward the following statement for the information of the general commanding the division:

Sunday morning, May 3, between 5 and 6 o’clock, the brigade, under Colonel Hayman, was in motion to take up a position and form line of battle.  Our regiment was nearest the woods where the enemy was. We were ordered to follow the Seventeenth Maine Regiment, Colonel Merrill.  While waiting for it to file off to the left and rear, the enemy drove a regiment out of the woods. I was ordered to form our regiment by Lieutenant Henry, on right by file into line of battle, and I engaged the enemy, who came out of the woods from every side, in great force, as fast as I could form the companies.  Before my regiment had time to form line of battle, a most terrific fire in front and on our flanks was poured into us, killing and wounding many men and officers. The regiment continued fighting and retiring. I rallied it as much as possible, but the enemy being in superior force, it retired along the flanks of our lines of battle, already formed, to the rear, and, as I supposed, to follow the regiments of our brigade which had already gone to form.  My horse became unmanageable. I was on foot, and rallied my men as best I could at General Hooker’s headquarters. I had some 50 or 60 men, supported the Tenth New York Battery.  Being informed that the greater portion of my men went down the road farther, I determined to collect them, all I could, and, as I went along, I found a great portion of our division going to the rear, which led me to believe that it was ordered there. I met a great portion of the Seventeenth Maine, under Colonel Merrill, a portion of the Third and Fifth Michigan, the First New York Volunteers, and the Sixty-third Pennsylvania Volunteers, and a great stream of men belonging to the Third Army Corps. I collected all the men of my regiment as they came along, and inquired from every officer I knew where our brigade and division were, and some seemed to know. I learned from Lieutenant Houghton, of Colonel Hayman’s staff, that a portion of the division was in front, and then I marched my regiment, all I could find of it, back to the front, together with all I could meet of the brigade and a greater portion of the division, about 1,000 men. I learned by several aides (Captain Smith, of Hayman’s brigade, and one of General Ward’s aides) where our division was. I immediately joined, and took my position in line.

Our loss in the morning’s fight was severe, among others Captain O’Beirne, Barley, and Murphy, and Lieutenants Kiernan (supposed to be killed), Markey, and Vosburgh, the latter supposed to be a prisoner; also my color-sergeant (Michael Lloyd). Total killed, wounded, and missing, 353.* My regiment  retiring so was owing to the fact that our brigade not being in position, and the attack of the enemy being so sudden, did not give it time to form.

Very respectfully, your obedient servant,

Gilbert Riordan,

Lieutenant-Colonel Thirty-seventh New York Vols., Commanding

Major  H.W. Brevoort,

Asst. Adjt. General, First Division, Third Army Corps.

*Subsequently Revised