The Neglected Ironclad, Feb. 23, 2012

The Neglected Ironclad:

A Design and Constructional Analysis

of the USS New Ironsides

The "New Ironsides" under sail


On 15 January 1865, at the beginning of the second combined Union assault on Fort Fisher, North Carolina, Rear Admiral David Dixon Porter wrote to Secretary of the Navy Gideon Welles that:  “I have never yet seen a vessel that came up to my ideas of what is required for offensive operations as much as the Ironsides.” Porter’s laudatory words elicit little modern recognition. In the public mind, the ironclads of the American Civil War are synonymous with the coastal and riverine monitors. Even in so exhaustive a history as James Phinney Baxter’s The Introduction of the Ironclad Warship, New Ironsides receives but a few lines. Yet, the seagoing New Ironsides participated in more engagements and fired more shots than any other armoured Union warship during the Civil War. The vessel’s contributions to the bombardments of Charleston and Fort Fisher were unmatched. New Ironsides, more than the coastal and riverine monitors, was more in the mainstream of ironclad development.

The aim of my presentation tonight is to provide a history of this little-known but fascinating Union warship. Accordingly, I will be outlining the genesis, the construction history, the “teething troubles”, the service experience, and the battle experience of New Ironsides and be comparing her briefly, first, to the Union coastal monitors and, second, to European ironclads of the period – specifically, HMS Warrior and the French La Gloire. I have not, however, made overheads of the slides to which I will be referring during the presentation. Instead, the slides are included in the packages that I distributed at the beginning of the meeting; each slide has a number and I will be referring to those numbers throughout the presentation for your guidance.


New Ironsides was conceived in response to an advertisement by the U.S. Navy Department on 7 August 1861. The advertisement requested proposals for “iron-clad steam vessels of war, of iron or of wood and iron combined”, to draw not less than 10 nor more than 16 feet of water. The advertisement, which included the requirement that the ship be rigged with two masts, stressed that “[t]he smaller draught of water, compatible with other requisites, will be preferred.”

A board of officers – the Ironclad Board – was appointed by Secretary of the Navy Gideon Welles on 8 August 1861 to examine the proposals that were expected to be received. The members of the Board were: Commodore Joseph Smith, then Chief of the Navy’s Bureau of Yards and Docks; Commodore Hiram Paulding; and Commander Charles H. Davis. These officers, none of whom were naval constructors, evaluated a total of seventeen proposals and recommended to Secretary Welles that three of them be accepted.

The three proposals that were accepted were of varying designs. The first, which became USS Galena – an ironclad, wooden corvette with tumblehome sides (“Tumblehome” is the curving-in of a vessel’s side above the waterline) and armour of interlocking bars – was proposed by Bushnell & Co, of New Haven, Connecticut. After suffering severely in an engagement at Drewry’s Bluff in May 1862, she was not considered to have been a success and, consequently, was removed from service in 1863 and converted to an unarmoured screw sloop. The second, proposed by John Ericsson, became Monitor. The third became New Ironsides, which is depicted in Slide 1.

New Ironsides was proposed by a Philadelphia firm that was well known for building marine steam engines. Samuel Vaughan Merrick had established the Southwark Foundry in 1839 and, by 1859, had taken his sons into what then became the well-established business of Merrick & Sons. The Merrick’s machinery was well known in the pre-War Navy. Among the vessels for which the firm had built engines were Mississippi, San Jacinto, and Wabash. While Merrick & Sons had no shipways of its own, the firm planned to subcontract construction of the hull to William Cramp and Sons, also of Philadelphia. Merrick & Sons tendered its proposal to the Navy Department on 3 September 1861, offering to complete the vessel within 9 months from the date of the contract award for $780,000.

While Merrick later credited B.H. Bartol, the superintendent of the Merrick works, with ”originating” New Ironsides, it is clear that the design was based heavily upon the French ironclad La Gloire, which is the smaller vessel shown in Slide 2; the larger one is HMS Warrior; and both vessels are shown to the same scale. Like La Gloire, the Merrick design was for a wooden-hulled vessel armoured with iron, with a broadside battery, and equipped with both sail and steam power. Slide 3 presents a comparison of New Ironsides with La Gloire and HMS Warrior.

The comparison shows some of the inevitable trade-offs that were made in the design of New Ironsides in pursuit of the Navy Department’s requirement for a shallow draft. (“Draft” or “draught” is the depth to which a hull is immersed. ­) The light draft was required for the vessel to be effective in the shallow waters of the Southern coast, but, as with all warship designs, meeting one characteristic required compromises in others. An analysis of 1867 noted the disadvantages imposed on a shallow-draft vessel:

Ist. Her lines must be more full (other things being equal), and hence more difficult of propulsion and manageability. 2dly. Her screw [propeller] must be smaller, and therefore less effective as an instrument of propulsion. 3dly. Her hull must be strengthened owing to lack of depth, and must, therefore, be heavier . . . .

As proposed, New Ironsides was to be a wooden-hulled vessel, 230 feet long at the waterline, and 56 feet in extreme beam. Her depth of hold – that is, the vertical space in the hold – was 24 feet 9 inches, and her draft, exclusive of her keel beam, was to be 14 feet. She was to be a 3-decked vessel, with a spar deck – the highest and only weather deck – a gun deck, and a berth deck above her hold.  With 6 feet clear between decks, she was roomy by the standards of the day.

The armour arrangement was the one later known as the “belt-and-battery” type. It included a belt of iron extending “entirely around” the vessel, from 4 feet below to 3 feet above the load line – that is, the waterline the water should reach when a vessel is properly loaded – which, in the instance of New Ironsides, was the 14-foot waterline. The first plate below the 14-foot waterline was to be 4.5 inches thick, and the second or lower plate 3 inches thick. Above the 17-foot waterline, the armour was to extend 170 feet only, or 85 feet each way from the centre of the vessel.

All the armour above the load line was to consist of “plates forged of the best American Scrap iron of 4.5 inches thickness, 15 feet long and 28 inches wide.” Each plate was to be grooved on all four sides, one inch deep and 1.5 inches wide; as the armour was installed, tongue pieces of iron would be placed in these groves, “so as to connect the several plates as one in their resistance to shot.” The armour was attached with wood screws with countersunk heads, which did not extend through the wooden hull. The spar deck was of iron, one inch thick, covered with 3 inches of yellow pine planking.

The main battery was located on the gun deck, or middle deck, and was intended to consist of 16 9-inch Dalhgren smoothbore guns. There was no protection from raking fire – that is, fire directed parallel to the long axis of an enemy vessel.

In her engineering plant, the proposed Merrick vessel was little different from the European vessels. The machinery was to drive the vessel at 9.5 knots. She was equipped with two horizontal reciprocating engines – that is, an engine in which the power is developed by a back-and-forth motion (such as a piston working in a cylinder) rather than by a rotary motion like a turbine – each with two cylinders of 50-inch diameter and 30-inch stroke, driving a single shaft of 10 inches in diameter. The brass screw propeller was to be 12 feet in diameter, considerably smaller than normal for a vessel of her size but all that could be accommodated on a design draft of 15 feet. New Ironsides had a clutch coupling fitted to permit the propeller to be disconnected from the engines. This common practice reduced drag while under sail by allowing the propeller to turn freely. As was the usual practice of the day, very little auxiliary machinery was provided.

The four boilers were of the horizontal fire-tube type, placed facing each other forward of the main engines. Numbers one and three boilers were on the port side, while numbers two and four were on the starboard. The hydrostatic test pressure – the pressure resulting from a test of the strength and leak-resistance of a vessel, pipe, or other hollow equipment by internal pressurization, with a test liquid – was 50 pounds per square inch, and the normal or working pressure between 20 and 25 pounds per square inch. Each boiler, 17 feet wide and 11 feet deep, had 6 coal furnaces, and all 4 boilers were connected to the same smoke pipe. There was also a single auxiliary boiler, to be used when the main boilers were not in use. The main boilers were fed with fresh water, made on board by a distilling plant that had a nominal capacity of 500 gallons per day; the auxiliary boiler was fed with salt water.

The vessel’s intended complement was 165 men, and the galley was built for 200, which caused difficulty later when the vessel’s complement was increased to almost 400 as the result of the substitution of 14 11-inch Dahlgren smoothbores and two 150-pounder Parrot rifles for the originally planned armament of 16 9-inch Dahlgrens.

The Merrick proposal fulfilled the Navy’s requirement for sail power by specifying two masts, but gave few details, in contrast to the carefully detailed listing of the machinery.

After the Ironclad Board had made its report on 16 September, the Navy Department commenced discussions with the 3 firms whose proposals had been recommended by the Board. While the building of vessels would normally be the responsibility of the Department’s Bureau of Construction, Equipment and Repair, the membership of Commodore Joseph Smith, the Chief of the Department’s Bureau of Yards and Docks, on the Ironclad Board impelled Secretary Welles to give responsibility for the first ironclads to Smith’s bureau.

The remainder of the month of September 1861 was occupied in negotiations between the parties. Merrick sent its superintendent, B. H. Bartol, to Washington for discussions on 27 September. The contract for the vessel was signed on 15 October, The contract included a guaranteed speed of 9.5 knots and a penalty of $500 per day for each day delivery was delayed beyond the contracted completion date.

Construction History

Construction of the vessel began almost immediately. Merrick & Sons subcontracted for the construction of the hull with William Cramp and Sons within a week after the primary contract had been signed. The Navy Department was involved with the construction from the very beginning, as Naval Constructor Henry Hoover, the Chief Constructor at the Philadelphia Navy Yard, prepared the details of laying down the vessel.

To supervise construction of the ironclad, Commodore Smith chose two experienced officers. On 14 November, Smith appointed Hoover and Chief Engineer William W. Wood as his inspectors. In their division of labour, Wood was to oversee the engineering plant and the armour, while Hoover was to oversee the rest of the vessel. Hoover had already been assigned to the Philadelphia Navy Yard, and Wood had reported for duty at the Navy Yard on 6 November.

Progress payments were a provision of the contract. The government paid the contractor every two weeks, beginning in December, and one of the duties of the inspectors was to certify that the contractor’s bills were correct. The standard increment for payment was $50,000, of which 25 per cent, or $12,500, was reserved by the government in case the vessel did not fulfill the contract specifications. Merrick & Sons apparently needed the money. When the Navy Agent in Philadelphia refused, on a technicality, to pay one warrant, W.H. Merrick wrote to Commodore Smith: “Excuse me for thus troubling you but in thin times money is a desireable article.” Merrick & Sons later claimed that the government’s slowness in making progress payments delayed the completion of the vessel.

As might be expected with so novel a vessel, the design process continued during the construction phase. The rigging design was at issue in December 1861, but a 3-masted bark rig was eventually chosen – that is, the fore- and mainmasts were square rigged and the mizzen set only fore-and-aft canvas. The vessel’s battery was in flux as late as 15 April 1862, when Commodore Smith wrote to Lieutenant John Dahlgren, Commander of the Washington Navy Yard and the Union Navy’s leading ordnance expert: “I have deck plans of ‘Ironsides’, also plans of shutting ports. Come up & see them & see how many XI inch guns she can fight.” The battery was again modified in July 1862, when the two 150-pounder Parrott rifles were moved from the spar deck to the gun deck.

The armoured shutters that covered the gunports were not included in the original design. The split shutters, 4 inches thick, pivoted at the top on an axle penetrating the vessel’s sides and were designed to be raised and lowered from within the battery. The shutters are visible in Slide 1.

The most significant additions during the vessel’s construction were the armoured bulkheads at each end of the battery. The original specifications did not include them. On 9 January, Merrick & Sons proposed them to Commodore Smith. The bulkheads were to run athwartships at each end of the battery, on both the gun deck and the berth deck below it. Each bulkhead was to be built of 12 inches of oak covered with 2.5 inches of iron.

On 16 January, Commodore Smith wrote back to say that the proposal had been “duly considered,” but he expressed concern about the effect of the bulkheads on the working of the anchor cables and a bow gun. His letter crossed one from Bartol, also dated 16 January, which gave an estimate of the added weight and enclosed a drawing. This letter was sent to the Bureau of Construction, Equipment and Repair for comment, and was returned with a note: “The disadvantages viz. weight above water and obstruction on deck are greater than any advantage we can perceive.” On the strength of this, Smith noted on 18 January: “Concluded not to put in the bulkhead.”

Fortunately for the Navy Department, Merrick & Sons did not drop the matter. On 13 February, Commodore Smith wrote again to Merrick & Sons indicating a willingness to accept the bulkheads as long as they did not affect the other characteristics of the vessel, especially her speed. Bartol replied for the company on 14 February, noting that: “We think the bulkheads absolutely essential between the spar and gun deck because a raking shot might disable several guns . . . an ironclad steamer is expected to be proof against an accident of this kind.” After receiving Bartol’s letter of 14 February, Smith, still concerned about increased weight and draft, approved the bulkheads between the spar and gun decks only.

An armoured pilothouse was also added at some time late in the construction of the vessel. The small circular structure was placed on the centreline of the spar deck, directly aft of the smokestack and mainmast.

The construction of New Ironsides, like that of Monitor, took longer than the contracted time. The vessel was launched on 10 May. By June, the engines were on board, and the armour was being installed. The vessel was docked on 6 June at the Philadelphia Navy Yard to install her copper sheathing and propeller. By 14 June, the propeller shafting had been installed, and Chief Engineer Wood was optimistic enough about prompt completion of the vessel to request permission to enlist firemen and coal heavers for the vessel. The boilers and engines were tested under steam during early July.

On 2 August, Secretary Welles directed Dahlgren, who, in July, had been promoted to the rank of captain and made Chief of the Navy Department’s Bureau of Ordnance, to ensure that the ordnance equipment was “hurried forward with all possible dispatch.” In reply, Dahlgren advised the Secretary that the iron gun carriages being made for the vessel would be completed by 11 August, although doing so required the dispatch of men from the Washington Ordnance Yard to assist one of the contractors.

The 9 months specified in the proposal had stretched to 10 by the time New Ironsides was finally completed. On 7 August, Merrick & Sons notified the Navy Department that construction of the vessel had been completed. There was still work to be done on the gun carriages, on the port shutters, and on the iron bulkheads, but these particular items were additional to the contract. Commodore Smith disagreed: “The contract is not complete til the Bulkheads are in . . . .”

The vessel was officially delivered to the Navy on 10 August. The armament was completed on 15 August, and the vessel was commissioned on 21 August, with Captain Thomas Turner, an officer of thirty-seven years experience, as Commanding Officer.

I should probably also note at this juncture that, as completed, the New Ironsides was described by Frederic Stanhope Hill, a former USN officer and later a writer on naval matters, in 1905 as “the personification of ugliness. She had neither graceful line or curve.” – a fact that is abundantly clear from Slides 1 and 4, which shows the lines, sheer and body plans of New Ironsides.

“Teething Troubles”

New Ironsides had little time for working up to full efficiency, since she was urgently wanted at Hampton Roads to counter the threat of the Confederate ironclads up the James River. After commissioning on 21 August, she started downriver on 22 August, in what her Commanding Officer, Captain Thomas Turner, called “unprecedented haste.” Her builder’s underway trials consisted of a passage down the Delaware River from Philadelphia to Cape Henlopen and the open-ocean passage from there to Hampton Roads. On 26 August, she anchored off Newport News. On 31 August, after the flurry occasioned by the Richmond-based Confederate ironclads had subsided, New Ironsides was sent to Philadelphia for post-trial repairs.

During her first trip, she displayed several failings, some best characterized as the “teething troubles” experienced in any new vessel, and some less easily corrected. The major tendencies revealed during her trials were speed – the vessel failed to make her guaranteed speed of 9.5 knots by a considerable margin – steering – the vessel became unmanageable as speed was increased, veering off to starboard; the problem was so severe that, at times, she had to be slowed or stopped to regain her course – and gun carriages – the gun carriage problem was one of excessive recoil, which risked injuring personnel and putting the battery out of action by breaking the carriages or dismounting the guns; the gun carriages for New Ironsides were of a new design, of iron instead of wood, and the plans for a carriage are shown in Slide 5.

The speed problem was never resolved. The steering problem was, in retrospect, probably due to the poor lines of the vessel aft, but, at the time, it was supposed that it was purely a rudder problem and was, therefore, “corrected” by changes to the steering gear and to the rudder itself. The problem of excessive recoil was, after much acrimonious correspondence between Dahlgren, Smith and Turner and much experimentation, finally resolved by the addition of a second compressor or shock absorber to each side of the gun carriages, by the installation of breechings – that is, stout restraining ropes running from a gun carriage through ring bolts on either side of a gunport – by a change in the 11-inch guns, from the “tulip” – that is, flared – muzzle variant to the straight muzzle one, and by placing ash wood on the slides of each carriage so that the gun rode upon the wood rather than upon the iron carriage directly.

While the vessel was correcting her difficulties and training in Hampton Roads, the Navy Department and Merrick & Sons were clearing up the contractual loose ends, chief among them the payment of the reservation money. A total of $195,00, or 25 per cent of the contract price, had been reserved by the government as surety for the vessel’s performance. The last progress payment was made on 13 August.

On 27 September, the government paid Merrick & Sons the sum of $34,322.06 “by bill of extras allowed by agreement.” This sum apparently included the bulkheads and, perhaps, the port shutters and pilothouse. On 4 October, despite the fact that the 90-day period had not yet expired, the Government paid Merrick & Sons $100,000 “on account of reservation.”

On 13 November, Merrick & Sons wrote to Secretary Welles requesting payment of the remaining reservation of $95,000. In his endorsement, Commodore Smith noted that the vessel was “highly spoken of except in speed in which she has simply failed to comply,” The balance due, without deducting the penalty of $500 per day for delayed delivery, was $93,719.27.

Under the circumstances, the government could hardly give up a perfectly serviceable ironclad just because she was three knots too slow. Secretary Welles, on 24 November, endorsed the request: “Admiral Smith will make a requisition on the Department to pay the balance [on] the ‘Ironsides’.”

Service Experience 

Her initial refit period behind her, New Ironsides joined the fleet in Hampton Roads during September 1862. She remained there until January 1863, when she went to Port Royal, South Carolina, where she made preparations to join the ironclad fleet at Charleston.

There were still two major items of work still to be done before she went into action. The first was to remove her masts and to replace them with thin poles, suitable for signalling but not for carrying sail. This modification was accomplished between 29 and 31 January. The other item was to cut down the smokestack so that it did not obscure the view from the pilothouse.

The placement of the pilothouse was undoubtedly poor. It was located on the centreline of the vessel, just abaft or behind the mainmast and the smokestack. Since the smokestack was some 8 feet in diameter and the pilothouse only 4, it was impossible to see straight ahead of the vessel from the pilothouse. The proposed solution was to cut down the stack to within about 4 feet of the spar deck. This item of work was accomplished on 26 January, and a trial trip around the harbour at Port Royal was undertaken the next day.

The experiment was not a success. The stack gas nearly suffocated those in the pilothouse as well as those on the gun deck, and the lack of draft made it almost impossible to open the boiler furnace doors to feed the fires. The smokestack was rebuilt, and the prospect of moving the pilothouse – also referred to as the “turret” – was investigated. Since the pilothouse weighted 18 tons, it was determined that it would be impractical to move it.

A major project, undertaken just before the first attack on Charleston, was to strengthen the spar deck. Since battle ranges during the War did not exceed 2,000 yards, projectile trajectories were flat, and it would have been unusual to receive a hit to the spar deck during a ship-to-ship action. Having been designed to fight other vessels, New Ironside’s deck protection was thin. Plunging fire from shore fortifications was another matter. Captain Turner wrote: “One inch of iron and three of wood upon her spar deck form a very feeble barrier to resist plunging shot, and bombs (that is, shells).” To strengthen her, the spar deck was covered with sandbags and green hides.

A design flaw that became even more sharply felt after the Charleston attack was the lack of armour protection at bow and stern. Captain Turner considered it “most important” to give the rudder “an iron-clad protection – in any way it can possibly be done.” No additions to the bow and stern protection were made, however, and the lack of protection for the bow and stern remained a vulnerability throughout New Ironside’s career.

Slow speed continued to be a problem. As experience mounted, it became evident that the 10-knot estimate obtained during the return to Philadelphia on her trial trip was in error. Chief Engineer William Wood reported in February 1863 that her best speed was 6.5 knots and, based on this trial, Turner noted that: “Six (6) knots is her maximum speed per hour. When passing up the Delaware last time . . . I gave her a higher rate of speed, but there was evidently a mistake . . . she can never have exceeded the rate I have given her here.” In May 1863, he reported to Rear Admiral Samuel F. Du Pont, commander of the South Atlantic Blockading Squadron, that: “This vessel is so unwieldy and moves so slowly . . . if they only knew that on shore they would not give themselves much trouble about her.”

In the technical bureaus of the Navy Department, opinion of her speed was similarly negative. John Lenthall, Chief of the Bureau of Construction and Repair, and Benjamin Isherwood, Chief of the Bureau of Steam Engineering, noted that New Ironsides had “just two-thirds of the speed guarantied [sic], and as the speed is in the ratio of the cube of the power, it follows that the contractor provided just one-third enough machinery, while the Government paid for two-thirds, and, in addition, paid very large extra bills.” The vessel’s best-logged speed was 7 knots under both full steam and sail.

Battle Experience 

New Ironsides was first tested in action during Rear Admiral Samuel F. Du Pont’s attack on Charleston on 7 April 1863. (See my presentation, entitled “Defunct Strategy and Divergent Goals: The Role of the United States Navy along the Eastern Seaboard during the Civil War”, delivered to the meeting of the OCWRT on 27 May 2010, for details of this action.) During this engagement, New Ironsides, serving as the fleet flagship, engaged the Charleston fortifications at relatively long range. This first action, and the battle damage she suffered, showed more both of the vessel’s deficiencies and strengths.

Chief among the deficiencies was her inability to properly function as a fleet flagship. Du Pont, in no good humour after the failure of his assault and not an enthusiastic supporter of ironclads, was caustic about the vessel: “The defects of the New Ironsides were glaring,” he wrote, “particularly the contracted size of her pilot house and its improper location behind the enormous smokestack, shutting out all view ahead and most materially interfering with the management of the vessel in battle . . .”

Captain Turner’s after-action report to Du Pont confirms three major deficiencies. First, the vessel was unmanageable in a tideway; second, the pilothouse was too small for more than three people; and, third, the vessel’s draft placed her within a foot of the bottom “frequently” during the action.

The small size of the pilothouse, with room only for Du Pont – who was not a small man – his pilot, and his fleet captain, was the most serious deficiency. The lack of room caused Captain Turner to take station on the gun deck, which meant that Turner, the officer most familiar with the vessel and most knowledgeable about her characteristics, could make no contribution to the difficult task of managing the vessel in action. Ship control, difficult enough under fire, was aggravated by the vessel’s being within a foot of grounding. The need for precise vessel control, and the frustration of being unable to obtain it, was certainly a factor in Du Pont’s management of the battle. From the description Du Pont gives of the battle, he undoubtedly found that manoeuvring of the flagship took much of his attention, which detracted from his ability to control the whole fleet.

It would appear that much of the vessel’s unmanageability was due to the unfamiliarity of Du Pont and his pilot with the vessel, or what her Executive Officer, Lieutenant Commander George E. Belknap, delicately called “wrinkles in the management of the helm.” The vessel later moved without difficulty up and down the same channel, at night and under fire. Belknap suggested that the vessel might have given a better account of herself had her own commanding officer and pilot been permitted to manoeuvre the vessel instead of Du Pont and his pilot, who did not come aboard New Ironsides until the morning of 6 April. The full underbody of the vessel combined with the shallow water to make steering difficult, and the articulated rudder probably aggravated the situation.

After the action, Captain Turner wrote to Commodore Smith: “It is an extremely hazardous thing – taking her over that bar at all – steering with the lower wheel – as badly as she does . . . I could not use the upper wheel – as we were within range of several batteries.”

The situation was later partially remedied by moving the lower or secondary steering wheel – also known as the “fighting wheel” – from the berth or lower deck to the gun deck, directly under the pilothouse. By shortening the reaction time between the conning officer’s orders and the helmsman’s response, the captain’s ability to direct the vessel in action was markedly improved. In addition, in December 1863, the pilothouse was enlarged.

During her first trial by fire, New Ironsides was struck by over 50 shot and shell. The damage she received set a pattern that was to be repeated in most of her engagements with fortifications. The damage can be divided into four general types: projectiles striking the side armour; projectiles striking the gunport shutters; projectiles striking the armoured spar deck; and projectiles striking unarmoured areas.

Projectiles that struck the side armour were of little concern. Shot and shell striking obliquely would glance off. Projectiles striking squarely would usually dent the armour, perhaps cracking it or denting the wooden backing behind it, without doing any significant damage.

Projectiles that struck the gunport shutters frequently broke them. If a shutter failed, it was generally because a projectile had struck it and caused it to break in two horizontally, and the detached lower portion of the shutter would then fall overboard. Replacement shutters were shipped from the North to be installed while the vessel remained on her blockade station. Few shutters appear to have been jammed either open or closed by projectiles.

Captain Turner had written to Commodore Smith on 2 April 1863 discussing the gunport shutters at some length. Turner worried that “should a shot strike the bolts upon which they pivot and vibrate – doubtless they would be disabled and perhaps the free action of them obstructed.” His plan for improving the shutters involved reshaping then to work “longitudinally on the vessel’s sides – instead of on the arc of a circle as now – moving in grooves fitted on the outside of the cladding.” They were to be held to the side of the vessel with bolts “through the entire wood of the vessel’s side and the cladding,” and operated by attaching tackles to bolts, which were in turn attached to the inside centre of each of the shutters. During the battle on 7 April, one shutter was carried away by a projectile “striking it just on the bolt.” The proposed alteration was apparently never carried out.

Projectiles that struck the spar deck were a more significant threat. In addition to penetration of the deck, Turner saw another problem “fraught with danger to the crews of the guns.” The spar deck planking was secured to the iron deck planking by wood screws about three inches long, which projected up through the iron into the wood. These screws were knocked loose from the overhead in the battery when a projectile struck the spar deck. Turner wrote that “. . . a shot striking anywhere over them drives them out – when corroded by the iron-rust – They fly out bodily – like bullets and would kill men standing underneath.” Turner’s fears were, however, apparently groundless. While the spar deck was hit repeatedly during various engagements, including projectiles that completely broke the deck plating, no serious injuries attributable to this cause were recorded.

Projectiles that struck the unarmoured, “soft” areas of the vessel generally caused no significant damage. Such projectiles were always a source of concern, however, since the lack of protective bulkheads between the gun deck and the berth deck and the lack of a protective deck other than the spar deck made the machinery and steering gear distressingly vulnerable. The problems with controlling the vessel were exacerbated by the need to minimize the unarmoured areas presented to enemy fire. The armoured bulkheads between the gun deck and the berth deck protected the battery itself. However, a projectile could pass through the spar deck and then through the gun deck forward or aft of the battery to reach the engines or rudder. Similarly, a projectile could pass through the stern above the armour belt and reach the rudder head and tiller.

Owing to New Ironsides’ difficulties in manoeuvring, the vessel did not make the contribution to the offensive that had been expected of her. Indeed, during the April 1863 attack on Charleston, she fired a total of only eight rounds. As she gained battle experience later, however, her battery came to be considered to be the most effective in the Union’s ironclad fleet, and this effectiveness made her a primary target of the Confederates at Charleston. One Confederate naval historian, J. Thomas Scharf, writes that New Ironsides was “more troublesome to Fort Wagner than all the monitors combined.”  Her fast and accurate gunnery was also remarked upon at Fort Fisher.

New Ironsides’ offensive success was due to her large battery and to the relative ease of working the guns that the broadside mounting provided, compared to the cramped turrets of the coastal monitors. After the troubles with the gun carriages had been resolved, the only deficiency noted was that the maximum elevation of the guns was just 4.5 degrees. This restriction, the result of the design of the gunports, limited the range of the guns to under 2,000 yards. It was a distinct handicap at Charleston, where the harbour was so shallow as to keep the vessel at a greater than optimum distance from the Confederate fortifications.

Comparison to the Coastal Monitors

In resistance to damage, New Ironsides was the equal of any of the coastal monitors, despite her unarmoured ends. She never had a man seriously injured in action. This circumstance was at least in part due to the protection given by her solid plating, which provided more resistance for the same total thickness of iron than did laminated plate. While the later monitors had some advantage in protection from their 11-inch turret armour, the major protective advantage of the monitors was their small target area. At Fort Fisher, the monitors “were fired at a great deal” but seldom hit.

New Ironsides’ broadside battery was far more effective than the turret batteries of the monitors in providing a high volume of fire. The monitors were more flexible though, since New Ironsides suffered from the defect of not being able to fire except on the broadside. The monitors had essentially unlimited firing arcs.

Due to the power of their 15-inch guns, the Passaic and Canonicus classes of monitor would have been more effective in ship-to-ship combat in protected waters. In the open ocean, however, the low freeboard of the monitors – freeboard is the vertical measurement from a vessel’s side amidships from the load waterline to the upper side of the freeboard or weather deck – would have left them unable to work their guns in a seaway, placing them at a disadvantage in an open-ocean battle.

In speed, New Ironsides was at a slight disadvantage. Rear Admiral John A. Dahlgren, who commanded Union naval forces at Charleston from early July 1863 and who was favourably impressed with the monitors, gave them 7 knots and New Ironsides 6 to 7. Due to her higher freeboard and good seakeeping qualities, New Ironsides would probably have been able to maintain her speed in a seaway.

It was in their shallow draft that the monitors had, under the conditions of the War, a decisive advantage. The monitors drew less than 12 feet of water, New Ironsides about 15. Dahlgren’s opinion was that a draft of 10 to 11 feet was the “most convenient” draft and that anything more was too restrictive. During the Charleston campaign, the light draft of the monitors made them the choice for inshore work, whereas New Ironsides was the only vessel suited for offshore work. The psychological impact of the original monitor aside, the reason the United States Navy built so many monitors and so few seagoing ironclads (New Ironsides, Galena, Dunderberg, Dictator, Puritan, Wampanoag, Madawaska) was that only vessels of very light draft could reach the fighting.

Dahlgren, who had served both in New Ironsides and in monitors while in action, summed up the discussion. He wrote: “Keeping in view the peculiar exigencies of the case, which required light draft and great ordnance power, it appears that the selection of the Department could not have been more judicious in preferring a number of monitors to operate from a heavy frigate as a base.” Together, both types of vessel provided both the inshore firepower and the offshore security required.

Comparison to European Ironclads

In comparison to her European contemporaries – HMS Warrior and La GloireNew Ironsides makes a favourable impression. While the smallest of the three, her protection and armament were the equal of the other two.

In terms of protection, the chief defects of New Ironsides were that her armour did not cover her bow and stern and that her deck armour was only one inch thick. As noted above, deck protection was not considered important in ship-to-ship combat. To avoid the weight of thick deck armour, minimal deck protection was common to all early ironclads. Warrior carried 0.75 inches of iron deck plating, and La Gloire only 0.40 inches.

New Ironsides had no armour above the waterline strake for some 30 feet forward and aft of the battery. (A “strake” is one continuous breadth of planking running from one end of a vessel to the other, either within or without board.) While her soft ends were vulnerable, so were Warrior’s. Warrior, with no waterline armour belt, had only the 0.75-inch plating of her hull to protect her fore and aft of the 213 feet amidships, which was covered by the 4.5-inch armour. La Gloire was the only one of the three vessels to have her sides completely covered with armour. As a result of the lack of protection to the stern, rudder damage was another significant danger. Neither New Ironsides nor Warrior had any protection for their steering gear.

A vulnerability common to all masted ironclads was dismasting. While New Ironsides had her masts removed for most of her war service, they would have been needed for operations in the open ocean, and both Warrior and La Gloire remained fully rigged throughout their careers. All three ironclads would have been liable to severe embarrassment in action by damage to a mast, because of the probability of fouling their propellers. (HMS Devastation [designed by Sir Edward Reed and launched in 1871] was the first of two Devastation-class mastless turret ships built for the Royal Navy. This class was the first class of seagoing capital ship that did not carry sails, and the first whose entire main armament was mounted on top of the hull rather than inside it.)

Shell would, of course, have been preferable to solid shot for inflicting damage to vessels. Theoretically, Warrior’s 68-pounders, firing a 49.6 pound shell could penetrate 4.5 inches of armour out to 250 yards, while the 136-pound shell of the 11-inch Dahlgren gun could penetrate out to 600 yards. However, no spherical shell of the period would have remained intact after penetrating armour. In practical terms, none of the three weapons could penetrate 4.5-inch plate using shell.

The only area in which New Ironsides would have been at a significant disadvantage was speed. Her service speed of 6 knots was well below the 14-knot trial speed for Warrior and the 12.5 knots claimed for La Gloire. Either European warship would have been able to catch or to evade New Ironsides at will. New Ironsides, with her superior battery and equal protection could discount any advantage the European vessels would gain from their ability to control the range of a battle, but she would not have been able to keep up with an enemy that desired to break off action.


As a seagoing ironclad in a coastal and riverine war, New Ironsides did yeoman service but gained no headlines. In the absence of a foreign enemy, her advantage over the monitors was discounted and her disadvantages emphasized. While experience with her led to improvements to the design of Dunderberg, a large, seagoing ironclad, the War ended before Dunderberg was finished, and that vessel was eventually sold to France. The monitors that were available for coastal defence in the immediate post-War years eliminated any support in the U.S. Congress to follow the evolutionary development of naval architecture as that that was being carried out in Europe. With New Ironsides’ decommissioning, the high-freeboard ironclad vessel type represented by New Ironsides died out in the United States Navy.

New Ironsides was in action more days than any other vessel of the Navy, and Admiral David Dixon Porter once wrote that New Ironsides had a reputation for having been pounded more thoroughly than any other vessel that ever floated. That comment can well stand as New Ironsides’ epitaph. The Navy received its money’s worth in New Ironsides.

On the evening of Saturday, 15 December 1866, New Ironsides burned to the water’s edge and sank at her moorings at the Philadelphia Navy Yard, perhaps as the result of the work of an incendiary or of a faulty heater.

By Edward Reed, and presented at the Ottawa Civil Round Table meeting, February 23, 2012


The principal primary sources for the presentation were the records of the Bureau of Yards and Docks in the U.S. National Archives and various reports and documents published in Official Records of the Union and Confederate Navies during the War of the Rebellion. The following books served as the chief secondary sources: Donald L. Canney, The Old Steam Navy; Howard J. Fuller, Clad in Iron: The American Civil War and the Challenge of British Naval Power; Robert Gardiner, ed., Steam, Steel and Shellfire: The Steam Warship, 1815-1905 (includes a chapter on the ACW and chapters on technological developments); Richard D. Hill, War at Sea in the Ironclad Age (includes a chapter on the ACW); Tony Gibbons, Warships and Naval Battles of the US Civil War; Paul H. Silverstone, Warships of the Civil War Navies, 1855-1883 (contains many illustrations, chiefly photographs, and basic technical details of individual ships); and Spencer C. Tucker, Arming the Fleet: U.S. Naval Ordnance in the Muzzle-Loading Era.