On returning to Colonel Williamson I observed our forces, which had entered the works away to my left, retiring, which of course added to our extreme peril. The Fourth Iowa was then drawing the concentrated fire of all the enemy's batteries and rifle-pits. I directed Colonel Williamson to hold the position, if possible, till I could get up re-enforcement,s but if he could not, to retire. Being on foot and completely exhausted, and the distance back so great, before regiments could be moved forward Colonel Williamson was compelled to bring off his regiment, which he did in good order. It was nothing but slaughter for it to remain. During the half hour it was there 7 men were killed and 104 wounded.

On inquiring of Colonel Abbott, of the Thirtieth Iowa, which was next in line to the Fourth Iowa, why he did not follow the Fourth, I found that after I had started he had been ordered by General Steele in person to turn off to the right to take another position. I had directed the commander of each regiment to follow the preceding one. The second regiment of my column being turned aside it broke my line, cutting off four regiments without my knowledge, leaving the Fourth Iowa going ahead alone.

The conduct of Colonel Williamson, his officers, and men through this trying ordeal is worthy of the highest praise.

Before I left I had placed my battery, the First Iowa, at the disposal of General Morgan, where it was actively engaged the rest of the day.

I am, very respectfully and truly, yours,

JOHN M. THAYER,

Brigadier-General, Commanding.

General MORGAN,

Commanding Third Div., Right Wing, Thirteenth Army Corps.

[Indorsement.]

HEADQUARTERS FOURTH DIVISION,
January 4, 1863.

Respectfully forwarded.

Thayer had only five regiments, one having been detached to make a orad.

FRED'K STEELE,

Brigadier-General, Commanding.

Numbers 20.

Report of Colonel James A. Williamson, Fourth Iowa Infantry, of skirmishes at Chickasaw Bayou and assault on Chickasaw Bluffs.

HEADQUARTERS FOURTH IOWA INFANTRY,
Battle-field near Vicksburg, Miss., December 30, 1`862.

CAPTAIN: I have the honor to make the following report of the part taken in the battle before Vicksburg ont he 28th and 29th instant by the Fourth Iowa Infantry.

Early on the morning of the 28th I took the position assigned me on the right of the brigade. In obedience to the orders of the general commanding the brigade I detailed 30 men from my regiment, under command of First Lieutenant E. C. Miller, of Company G, to act as pioneers and skirmishers. Of these 30 men 1 was killed and 5 wounded during