The following is taken from Catesby ap Roger Jones's (Executive Officer of the CSS Virginia) publication for the Southern Historical Society, October, 1874. [Mabry]
A lithograph of the original USS Merrimack (Catesby Jones
served on the USS Merrimack to test out the first Dahlgren
guns ever installed):
(See also Captain Wright's report on the US Navy's attempt to destroy the Norfolk Navy Yard before retreating on April 21, 1861.)
When on April 21st, 1861, the Virginians took possession of the abandoned navy yard at Norfolk, they found that the Merrimac had been burnt and sunk. She was raised; and on June 23rd following, the Hon. S. R. Mallory, Confederate Secretary of the Navy, ordered that she should be converted into an ironclad, on the plan proposed by Lieutenant Jno. M. Brooke, C. S. Navy.[E1]
The hull was 275[E2] feet long. About 160 feet of the central portion was covered by a roof of wood and iron, inclining about 36 degrees. The wood was two feet thick; it consisted of oak plank 4 inches by 12 inches, laid up and down next the iron, and two courses of pine, one longitudinal of eight inches thickness, the other twelve inches thick.
The intervening space on top was closed by permanent gratings of two-inch square iron two and one-half inches apart, leaving opening for four hatches, one near each end, and one forward and one abaft the smoke-stack. The roof did not project beyond the hull. There was no knuckle as in the Atlantic,[E3] Tennessee and our other ironclads of later and improved construction. The ends of the shield were rounded.
The armor was four inches thick. It was fastened to its wooden backing by one and three-eighths inch bolts, countersunk and secured by iron nuts and washers. The plates were eight inches wide. Those first made were one inch thick, which was as thick as we could then punch cold iron. We succeeded soon in punching two inches, and the remaining plates, more than two-thirds, were two inches thick. They were rolled and punched at the Tredegar Works, Richmond. The outside course was up and down, the next longitudinal. Joints were broken where there were more than two courses.
The hull, extending two feet below the roof, was plated with one inch iron; it was intended that it should have had three inches.
The prow was of cast iron, wedged shaped[E4], and weighed 1500 pounds. It was about two feet under water, and projected two feet from the steam; it was not well fastened.
The rudder and propeller were unprotected.
The battery consisted of ten guns, four single-banded Brooke rifles and six nine-inch Dahlgren's shell guns. Two of the rifles, bow and stern pivots, were seven-inch, of 14,500 pounds; the other two were 6.4 inch (32 pound calibre) of 9000 pounds, one on each broadside. The nine-inch gun on each side nearest the furnaces was fitted for firing hot shot. A few nine-inch shot with extra windage were cast for hot shot. No other solid shot were on board during the fight.
The engines were the same the vessel had whilst in the United States Navy. They were radically defective, and had been condemned by the United States Government. Some changes had been made, notwithstanding which the engineers reported they were unreliable. They performed very well during the fight, but afterwards failed several times, once whilst under fire.
There were many vexatious delays attending the fitting and equipment of the ship. Most of them arose from the want of skilled labor and lack of proper tools and appliances. Transporting the iron from Richmond also caused much delay; the railroads were taxed to supply the army.
The crew, three hundred and twenty in number, were obtained with great difficulty. With few exceptions they were volunteers from the army; most of them were landsmen. Their deficiencies were as much as possible overcome by the zeal and intelligence of the officers; a list of them is appended. In the fight one of the nine-inch guns was manned by a detachment of the Norfolk United Artillery.
The vessel was by the Confederates called Virginia. She was put in commission during the last week of February, but continued crowded with mechanics until the eve of the fight. She was badly ventilated, very uncomfortable, and very unhealthy. There was an average of fifty or sixty at the hospital, in addition to the sick list on board.
The flag officer, Franklin Buchanan, was detained in Richmond in charge of an important bureau, from which he was only relieved a few days before the fight. There was no captain; the ship was commissioned and equipped by the executive and ordnance officer, Catesby ap R. Jones[E5], who had reported for duty in November. He had by special order selected her battery, and was also made responsible for its efficiency.
A trial was determined upon, although the vessel was in an incomplete condition. The lower part of the shield forward was only immersed a few inches, instead of two feet as was intended; and there was but one inch of iron on the hull. The port shutters, etc., were unfinished.
The Virginia was unseaworthy, her engines were unreliable, and her draft, over twenty-two feet, prevented her from going to Washington. Her field of operation was therefore restricted to the bay and its immediate vicinity. There was no regular concerted movement with the army.
 There was however, an informal understanding between General Magruder, who commanded the Confederate forces on the Peninsula, and the executive officer, to the effect that General Magruder should be kept advised by us, in order that his command might be concentrated near Hampton when our attack should be made. The movement was prevented in consequence of a large portion of the command having been detached [E6] before the fight.
[E1] The United Service version has "John M. Brooke, Confederate States Navy", the Mabry version has "Jno. M. Brooke, C. S. Navy".
[E2] The United Service version usually spells out numbers while the the Mabry version usually had digits. Other minor differences include differences in hyphenation, occasional spelling differences (plural vs singular, "draught" vs "draft", "afterwards" vs "afterward"), and minor word differences ("fired at" vs "fired on", "fight" vs "fighting", "in" for "into", "enabled" for "able").
The following names are different in the United Service version vs the Mabry version: "Drewry's Bluff" vs "Drury's Bluff", "Marmaduke" vs "Marmeduke", "Roots" vs "Rootes", "Tynan" vs "Tyan"
[E3] "Atlanta" in the United Service version.
[E4] "wedge-shape" in the United Service version.
[E5] "Catesby ap R. Jones" was not in the United Service version.
[E6] "just" is inserted here in the United Service version.