The US Navy from 1790 to the Civil War
The United States was without a navy for nearly a decade after the achievement of independence. This exposed its merchant ships to a series of attacks by Barbary pirates. The sole armed maritime presence between 1790 and the launching of the US Navy’s first warships in 1797 was the US Revenue Cutter Service (USRCS), the primary predecessor of the US Coast Guard. Although USRCS Cutters conducted operations against these pirates, the depredations far outstripped the capabilities of the USRCS and on 27 March 1794 Congress ordered the construction and manning of six frigates. Three years later the first three entered service: the USS United States, USS Constellation and USS Constitution.
After a brief conflict with France, the US Navy saw its first substantial action in the War of 1812, where it was victorious in eleven single-ship duels with the Royal Navy. The US Navy drove all significant British forces off Lake Erie and Lake Champlain and prevented them from coming under British control. However, the US Navy was unable to prevent the British from blockading American ports and landing troops on American soil. After the war, the US Navy focused its attention again on protecting American shipping, by sending squadrons to the Caribbean, the Mediterranean, South America, Africa and the Pacific.
During the Mexican-American War of 1846-1848, the US Navy established blockades of Mexican ports, captured or burned the Mexican fleet in the Gulf of California and captured all major cities in the Baja California peninsula. The Pacific Squadron under Commodore (Rear Admiral) Robert Stockton contributed marines and sailors to assist in the capture of California alongside local militia forces in the California Battalion. The navy conducted its first large-scale amphibious operation by successfully landing 12,000 army troops with their equipment in one day at Veracruz, Mexico. When larger guns were needed to bombard Veracruz, Navy volunteers landed large ships’ guns and manned them in the successful bombardment of the city until its surrender. The capture of Veracruz eventually opened the way for the capture of Mexico City and the end of the war. The US Navy established itself as a major factor in American foreign policy through the actions of Commodore Matthew Perry in Japan, and the Convention of Kanagawa in 1854.
Changes in Naval Warfare 1840 to 1860
Naval science changed little during the two centuries prior to 1840. Improvements in construction, equipment and ordnance came about slowly and gradually and while many mechanical innovations were adopted and old designs rendered more efficient, no fundamental changes occurred in the art and principles of naval warfare. Warships remained essentially unchanged for two hundred years, rigged and propelled by sail, and armed and fought upon well-established principles.
The introduction of steam as a reliable motive power marked the beginning of an era of rapid and radical change from about 1840 onwards. Within thirty years the sailing vessel was superseded in the military sphere for almost all purposes except training. The steam-driven paddle-wheel steamer was followed quickly by the screw propeller and then by the twin-screw. The rig of ships changed, and spars and sail-spread were gradually reduced until they were no more than auxiliary to mechanical propulsion. Gradually it was realised that the danger from falling spars and fire presented a danger out of proportion to the benefit of auxiliary sail-power and soon vessels were built with no spars above the deck except for a signal-pole forward and aft.
The familiar system of naval tactics was also forced to change by the introduction of steam propulsion. The close-hauled line ahead under sail, an order of battle used for two hundred years and more, gave way to directs attack by ships in line abreast. The direction of the wind, which had dictated and dominated manoeuvre for centuries, became almost irrelevant.
Steam power revived the use of a weapon from ancient times. The ram, which had been the principal weapon of naval warfare in Greek and Roman galleys driven by oars, had long been replaced by sailing ships armed with guns and manned with boarding crews. Soon after the introduction of steam some naval officers proposed that steam-driven rams might be employed to great advantage as modern warships. The revival was short-lived but arguments about the value of steam rams persisted until after the Civil War.
Naval artillery also underwent a considerable change, as guns became more powerful, more accurate and longer in range. Calibres increased significantly through improvements in metallurgy and foundry technology. This meant that battles could be fought at a distance where close combat, ramming and boarding were unlikely to arise. Guns were adapted to fire fused explosive shells, which had hitherto been confined to mortars, and explosive power added to the destructive momentum of solid shot. Rifling of barrels was more widely adopted, providing greater range, accuracy, and penetration. Finally, breech-loading guns came into use, allowing more rapid reloading from inside a protective casemate. Guns were gradually transferred from traditional broadsides into elevated citadels or turrets, allowing a wider sweep forwards and around the horizon: the reliance on massed close-range gunfire gave way to sophisticated gunnery techniques to fire highly-destructive projectiles at longer ranges.
Following closely upon the improved effectiveness of guns, came the demand to protect vessels with armour. Armour was first made of light bar iron or plates but experiment soon developed sheets of solid steel up to twenty-two inches in thickness. The big-gun armoured warship was to dominate military sea power for almost a century until the advent of air power.
The explosive spar torpedo, which had been used tentatively as early as 1776, also made its way into the armoury of naval weapons. This was soon supplemented by fields or cordons of underwater torpedoes (naval mines) laid in rivers or at sea. Primitive submarines also evolved to a point where innovative tacticians saw the value of this potent new threat.
Modernisation of the US Navy 1840 to 1860
There were many harbingers of change before 1840 but the results of the naval revolution were to be tested on a large scale during the American Civil War. From 1840 to 1860 the US naval administration, like its counterparts in Europe, endeavoured to keep up with the radical changes in technology and tactics that were taking place. By 1860 the United States was viewed as one of the first world powers to realise the impact of steam and the navy was generally ranked third in efficiency behind Great Britain and France.
The US Navy began to construct its first heavy side-wheel steamers as early as 1847, firstly the USS Mississippi and USS Missouri and later the USS Powhatan and USS Susquehanna. The latter vessels were considered to be modern and efficient when launched in 1850 but the design was dropped as soon as the new submarine screw propeller replaced the vulnerable paddle-wheel. Six new screw-driven frigates were built in 1855, and they were highly regarded abroad as well as in the USA. The largest of these was the USS Niagara, displacing 4,500 tons. The other five, the USS Roanoke, USS Colorado, USS Merrimac, USS Minnesota and USS Wabash, each had a displacement of over 3,000 tons. They were heavily armed for their size, and they were intended to form the chief element of naval strength for the United States. The reliance of the US Government on this fleet of large steam frigates was sound and, in a war against a maritime enemy equipped with similar vessels, they would have served effectively. However, the Confederates had only a negligible fleet of conventional warships and their coastal waters were usually too shallow to admit the steam frigates. Therefore, despite their merits, these ships did not serve decisively or proportionately to their size and costs of maintenance, except in the bombardment of coastal fortifications.
A group of twelve new screw-driven sloops built in 1858 proved to be more useful type of warship. There were five in the first class, the USS Hartford, USS Brooklyn, USS Lancaster, USS Pensacola and USS Richmond. Sloops of the second class were the USS Michigan, USS Narragansett, USS Dacotah, USS Iroquois, USS Wyoming and USS Seminole. To this group also belonged the USS Pawnee, a vessel of peculiar construction, whose constant service was to be unsurpassed by any other ship serving on the Atlantic coast. Besides these twelve screw sloops, there were a few steamers of miscellaneous dimensions and character, some of which had been purchased and altered for naval use. These ships comprised the rudiments, but no more, of a modern steam-driven fleet.
The Union Navy at the Outbreak of War
The strength of the US Navy had usually ranged from 80 to 100 vessels and in early 1861 the total was 90 vessels in the active list. Many old vessels were counted in this list and some had even seen service as far back as the War of 1812. Fifty were sailing ships, classed either as line-of-battle ships, frigates, sloops or brigs. These had all been useful in their day, but they were rapidly becoming obsolete. They were supplemented by the forty vessels of the modern steam-driven fleet. At the beginning of the war, only about 35 of the 90 active ships were ready for active service and the remainder were laid up at various dockyards awaiting repairs.
The readily serviceable navy consisted of two sailing frigates, eleven sailing sloops, one screw frigate, five screw sloops of the first class, three side-wheel steamers, eight screw sloops of the second class and five screw sloops of the third class. Available but laid up in various yards for repair and refitting were eighteen sailing ships, five screw frigates, one screw sloop and three or four side-wheel steamers. Nine were laid up and some months were required to fit them out for sea.
In the Home Squadron there were seven steamships. The sloop-of-war USS Brooklyn and the small steamer USS Wyandotte were at Pensacola; the gunboats USS Mohawk and USS Crusader were at New York; the sloop USS Pawnee was at Washington; and the 1850 side-wheeler Powhatan was on its way home from Vera Cruz in company with the gunboat USS Pocahontas. Five other ships were attached to this squadron. The sail frigate USS Sabine and the sloop USS St Louis were at Pensacola; the sailing sloops USS Cumberland and USS Macedonia were at Vera Cruz or returning home, and the store-ship USS Supply was at New York. These twelve vessels, together with the USS Anacostia, a small screw-tender at the Washington Navy Yard, were all that could be placed at the immediate disposal of the Administration. USS Michigan was stationed on the Great Lakes, and five more ships were unserviceable for various reasons.
The remaining thirty-four ships were dispersed around the world as is usual in peacetime. Orders were not issued immediately for the general recall of the seventeen ships on foreign service, an operation requiring considerable time before the development of submarine telegraph cables. For example, USS Niagara was on special duty in Japanese waters and could not report for several months. The other ships on foreign stations required from a week to a month to regain home waters. Of the forty-eight ships that were in dock or in the navy-yards, none could be prepared for service within a fortnight and many would require a month or more before they could be ready.
The US Navy Department was dealt a severe blow by the early loss of the Gosport Navy Yard in Norfolk, Virginia. Some of the navy’s most formidable and most historic ships, including the steam frigate USS Merrimac, the sloops USS Germantown and USS Plymouth and the brig USS Dolphin were all laid up for repair and destroyed after the state’s secession. In addition, the sailing line-of-battle ship USS Pennsylvania, USS United States, USS Columbus, USS Delaware, USS Rariten and USS Columbia, as well as the unfinished ship of the line USS New York were also lost. Over $2,000,000 worth of Federal property was destroyed at Norfolk, while great quantities of stores and ammunition and thousands of cannons fell into Confederate hands. Other vessels which could not be removed from docks or naval stations were either seized by the seceded states or the Confederate Government or destroyed by order from Washington.
When all the vessels abroad were recalled and those laid up were fitted out, the Government could deploy about 30 steam ships, of which the most important were the remaining five screw-frigates (the sixth, the USS Merrimac having been burned at Norfolk). There were six sloops of the first or Hartford class, four large side-wheelers and eight sloops of the second or Iroquois class. All were valuable as the nucleus of a fleet but for the kind of war now underway they were insufficient and inappropriate. A fleet capable of raids upon the enemy’s warships, commerce or seaports might prove advantageous to the Confederates, but the Federal Government required materials and methods of a different character. The US Navy was required to blockade the seceded states and required a cordon of fast and efficient steamers patrolling four thousand miles of coastline. The reduction and passage of coastal and riverside fortifications required a powerful and well-equipped fleet designed for the purpose. The vast network of interior waterways which were essential to the army’s supply and communications could only be held successfully by another numerous and unusual kind of fleet. Finally, the protection of commerce demanded a squadron of fast cruisers.
The Expansion of the US Navy
From the very first, the Federal administration understood the maritime vulnerability of the Confederacy and realised that Confederate dependence on imported supplies and the need to export staple crops, especially cotton, might prove fatal. The primary missions of the Union Navy were quickly confirmed as four-fold:
- To maintain the blockade of Confederate ports declared by the US President on 19 April 1861 and to inhibit blockade-running;
- To oppose the warships of the Confederate States and, increasingly, to suppress raiders operating against US merchant shipping;
- To project the Union army to places inaccessible by overland routes, but reachable by sea and navigable waters, and to reduce strategically important defences on Confederate coasts and rivers;
- To support the Union Army with gunfire support, rapid transport, supply and communications on the rivers of the interior.
To accomplish the novel missions required by the conflict, the Union Navy had to undergo a profound transformation, both technically and institutionally. During the course of the war, sailing vessels were almost wholly supplanted by ships propelled by steam for purposes of combat. Vessels of widely differing character were built in response to the peculiar problems they were required to surmount. Wooden hulls were at first protected by armour plating and soon afterwards vessels were armoured entirely by iron or steel. Guns were reduced in number but increased in size and range. The reduction in number was partially compensated for by the mounting of guns in rotating turrets that could fire in any direction.
As the US Navy was not large enough to operate immediately on a war footing, makeshift measures were adopted for its rapid increase and adaptation. The force was increased immediately by the purchase of great numbers of vessels of all kinds. Of these, thirty-six were side-wheel steamers, forty-two were screw steamers, one an auxiliary steam bark, and fifty-eight were sailing craft of various classes. These vessels mounted a total of five hundred and nineteen guns, of which the steam craft carried three hundred and thirty-five. The Navy Department eventually purchased 418 vessels during the war, and these included every variety of merchantman and river steamboat crudely adapted for war service.
Three types of new wooden vessels were built. There were 14 screw sloops of the Kearsarge, Shenandoah and Ossipee classes, 23 screw gunboats known from the rapidity of their construction as “ninety-day” gunboats and 47 side-wheel steamers known as “double-enders,” for service in narrow channels where they could move ahead or astern without turning. Later in the war forty-eight additional sloops or corvettes of various sizes were projected but few were finished before the close of the conflict. By the end of 1861, twenty-three ships were already under construction in Government shipyards and one was being built at the New York Navy Yard by a private contractor. Every place where serviceable ships could be laid down was soon put to use and at the close of 1861 private yards were building a further twenty-eight sailing vessels, fourteen screw sloops, twenty-three screw gunboats and twelve side-wheelers. The US Navy eventually built two hundred and eight vessels and purchased four hundred and eighteen. Of these, nearly sixty were ironclad warships, mostly of the monitor design. The principal yards for the construction of Federal ships were at New York, Philadelphia, Portsmouth and Boston.
Administration of the US Navy
The personnel of the Navy were inadequately prepared for war. As there was no system of retirement, and as promotion had been made solely on the basis of age and seniority for many years, the higher part of the list was filled with officers who had grown too old for active service but who were entitled by seniority to important commands at sea, in council or in administration. Many were unfitted to these duties through their outdated views and experience. The seventy-eight commodores and captains who were the most senior officers of the navy, with few exceptions, were very conservative and relics of the bygone age of sail.
During the long period of peace which lasted, with brief interruptions, from the war of 1812 until 1861 the US Navy became increasingly conventional and conservative. Reliance upon rank and age tended to make senior officers authoritarian and inflexible and junior officers suffered from an impaired power of initiative. The high command of the service was largely unprepared to meet the challenge of war and this contributed to the slow evolution of naval operations during the early part of the war.
In addition to command weaknesses, the junior grades were short of trained and competent officers. The Naval Academy had been only recently established and limitations in opportunities for appointment had led to the loss through resignation of many competent officers. To fill the gaps, training at the Naval Academy was temporarily curtailed at the outbreak of war and the older classes were ordered immediately into active service. The Naval Academy was removed for security to Newport, Rhode Island until 1865 when it returned to Annapolis, Maryland. On 1st August 1861, the total number of officers of all grades and corps holding regular appointments in the navy was 1,457. This number was inadequate for the expanding fleet, and 7,500 volunteer officers were enrolled in the navy during the war. These came mainly from the merchant marine. Many were capable mariners but their lack of naval (as opposed to nautical) training slowed their development as leaders of warships.
A larger increase occurred in the number of enlisted seamen even though there was no reserve or militia force to form a nucleus for expansion. The pre-war complement of seamen was 7,600 and this rose during the war to 51,500, although it was often difficult to obtain recruits. In total, the Union Navy employed 84,415 personnel. It was generally more difficult to secure enlistments for the navy than for the army, and with the constant addition of new ships it became necessary to offer large bounties to naval recruits in order to acquire enough men to crew the ships. Training was often inadequate among the crews as well as with the officers. The Navy Department was encumbered at the outbreak of war by growing numbers of “contrabands” or runaway slaves seeking protection in the navy yards or aboard ships. These contrabands could not be deterred and on 25th September 1861 an order was given permitting contrabands to be employed as crewmen on Federal vessels or in the navy yards and this provided a valuable source of labour.
The central office of naval administration was also unprepared for the demands of naval war and the measures necessary to put the navy into efficient operation. The plan of campaign, the recruitment and training of officers and men, the expansion of the fleet and the acquisition of modern weapons and vessels had to be resolved after the war had begun as contingency plans were almost non-existent. However, the possession of well-equipped shipyards and a large merchant fleet from which to draw both vessels and men enabled the Union to increase its fleet and to improve its efficiency at sea. Access to manufacturing and engineering establishments of all kinds contributed to the success of the Union cause, as did the technical skills of mechanics and inventors in the development of new techniques and technology.
The Secretary of the Navy Gideon Welles had been connected with the Navy Department as civil chief of the Bureau of Provisions and Clothing prior to 1849, but he was not a naval expert. He was obliged to rely on others for expert advice and assistance, but the five chiefs of bureau were concerned only with the business of supply and had little to do with the direction of the fleet in naval operations. The Secretary appointed Captain Gustavus Vasa Fox to the post of chief professional adviser. Fox was a former officer of the Navy and had a high reputation for professional skill. His connection with manufacturing enterprises during the few years before the war had given him knowledge and experience unusual among serving naval officers. He performed the role of a chief clerk from May 9th 1861 but in July, Congress created the office of Assistant Secretary, to which Fox was appointed on August 1st 1861. He was succeeded as chief clerk by William Faxon. At the head of the bureau of yards and docks was Joseph Smith, who had held the position since 1845. The bureau of ordnance and hydrography, the bureau of construction, equipment and repair, the bureau of provisions and clothing and the bureau of medicine and surgery completed the available onshore administration. By an act of Congress on July 5th 1862, the bureau of navigation and the bureau of steam engineering were added. At the same time the bureau of construction, equipment and repair was divided into the bureau of equipment and recruiting and the bureau of construction and repair. Early in 1862, the number of artisans and labourers employed in the construction and equipment of new ships in the Government navy yards was increased from less than 4,000 to nearly 17,000. Similar numbers were engaged by private contractors to build and equip vessels for the service.
Most importantly, the set of officer ranks was re-defined to assign each naval rank an appropriate equivalent in the Army. The highest rank available to an American naval officer when the war began was that of captain. In early joint operations of the Army and Navy, the traditional rank equivalency between the two services meant that a naval captain was equivalent to an army colonel, and therefore almost invariably inferior in command to any General officer. The case was soon made that the interests of the nation would be better served by organising the Navy along lines comparable to the Royal Navy of Great Britain. A set of new officer ranks and equivalents was established in the summer of 1862 that matched the set of Army ranks. The creation of the new ranks also reflected a doctrinal change of naval operations. Prior to the war, the US Navy had rarely operated more than a few vessels, but the single-ship and small flotilla operations of the past were inapplicable in the new conflict. Uncertainty in the chain of command in naval forces was exacerbated by a complex, if not incomprehensible, system of hierarchy dependent on seniority by length of service. The deployment of substantial fleets occurred as early as Port Royal on 7 November 1861 when 77 vessels, including 19 warships, were employed. This was the largest naval expedition that had ever sailed under the American flag but subsequent operations at New Orleans, Charleston, Mobile, Fort Fisher and even on the inland waterways also employed large fleets. The most significant change was that the designation of new ranks of commodore, rear admiral, vice admiral, and eventually admiral. These were all new formal ranks, and equivalent to Brigadier-General, Major-General, Lieutenant-General and General. By the end of the war, the structure of officer ranks in the Union Navy was established, in order of priority as Admiral, Vice Admiral, Rear Admiral, Commodore, Captain, Commander, Lieutenant- Commander, Lieutenant, Master and Ensign.
Naval Support for the Invasion of the South
The two earliest invasions of the South were meant primarily to improve the blockade, and then led to further military operations. Following the capture of Cape Hatteras, much of coastal North Carolina was soon occupied by the Union Army. The Union army maintained a strong presence, threatening railroads inland and the possibility of cutting supplies to Virginia from the southernmost states. This success was not repeated after the early seizure of Port Royal in South Carolina, as determined resistance prevented any significant expansion of the army’s foothold. Charleston did not fall until the final months of the war, by which time its importance as a base of operations had diminished.
The capture of Fernandina in Florida was intended to provide an anchorage for the blockade in the South Atlantic. This resulted in the gradual occupation of Jacksonville and the southern sounds of Georgia, but this was did not contribute significantly to the overall campaign. Union naval supremacy forced the Confederate government to assign strong forces to defend its major ports, but these fell successively to joint operations, naval attacks or capture from the landward side.
The capture of New Orleans contributed only marginally to the blockade, as the Mississippi was already sealed, but the passage of the forts below the city showed that traditional or even modern coastal fortifications could not resist the passage of vessels powered by steam. It also confirmed that the plan of severing the Confederacy along the line of the Mississippi River was practicable. Additionally, the fall of the great commercial centre cast doubt on the ability of the Confederacy to establish itself, and thereby deterring European nations from granting diplomatic recognition or intervention.
The last important naval action of the war was the capture of Fort Fisher, at the mouth of the Cape Fear River in North Carolina. The Army and Navy cooperated with great efficiency in the bombardment, landing and assault. This sealed off Wilmington, the last port open to the Confederates. A major force marched inland and combined with the main armies operating in Virginia and South Carolina to force final surrender within four months of the victory.
The Union Blockade
Almost the first act of war was to declare a blockade of the Atlantic coast south of Chesapeake Bay, and this was quickly followed by proclamations extending it from the Gulf of Mexico to the Rio Grande. This was proclaimed long before there were enough vessels to make the blockade effective but as the US Navy grew in size most of the newly purchased ships were used to establish and strengthen the blockade. By the end of 1861 all of the ports of the Confederacy were guarded in varying degrees of security by vessels cruising offshore. The work became increasingly demanding as blockade runners began to attempt the dangerous game of eluding the cordon. Although it was an unglamorous and arduous task, maintenance of the blockade was the most important role of the navy and its absorbed the greatest part of its resources.
The Union naval ships enforcing the blockade were divided into squadrons based on their area of operation. In May 1861, there was single blockading squadron (Coast). Almost immediately it was split into two segments (Atlantic and Gulf). In October 1861 the Atlantic Squadron was divided into two sections, North and South. Soon afterwards in January 1862, the gulf Squadron was also divided into two segments, East and West. These four squadrons continued in action beyond the end of hostilities and were not disbanded until June/July 1865.
Coast Blockading Squadron
Following President Abraham Lincoln’s proclamation of a blockade of Southern ports on April 19th 1861 the US Navy Department subdivided the territory formerly assigned to the Home Squadron. This resulted in the creation of the Coast Blockading Squadron in early May 1861. In orders sent on May 1st 1861 Secretary of the Navy Gideon Welles appointed Flag Officer Silas Horton Stringham to command the Coast Blockading Squadron. Stringham took command on May 4th 1861 with headquarters at Hampton Roads, Virginia. The Coast Blockading Squadron was given responsibility for the blockading of the coast from the capes of the Chesapeake to the southern extremity of Florida and Key West.
Atlantic Blockading Squadron
On May 17th 1861 the Coast Blockading Squadron was re-designated the Atlantic Blockading Squadron. On September 16th 1861 Stringham resigned as commander of the squadron following his receipt of a letter from Acting Secretary of the Navy Gustavus Vasa Fox that he felt indicated disapproval of his measures to enforce the blockade. Stringham’s resignation was accepted on September 18th 1861 and the same day Flag Officer Louis Malesherbes Goldsborough was appointed as his replacement. The transfer of command took place on September 23rd 1861 when Goldsborough arrived at Hampton Roads. In communicating to Goldsborough about his appointment Gideon Welles stated that “more vigorous and energetic action must be taken” to enforce the blockade.
On May 17th 1861 fourteen ships were assigned to the squadron, supplemented by the “Flying Flotilla” (later the Potomac Flotilla) which was being formed by to protect the Chesapeake Bay area. The Potomac Flotilla acted independently under the direct orders of the Navy Department, though there was some transfer of vessels with the Atlantic Blockading Squadron. With the acquisition and arming of civilian vessels the Atlantic Blockading Squadron gradually grew to about three times its original allocated strength.
The only major operation conducted by the Atlantic Blockading Squadron was the expedition that led to the capture of Hatteras Inlet, North Carolina August 26th – 29th 1861. This goal of the operation was to deny use of the inlet to Confederate shipping and this was accomplished with few casualties.
During the summer of 1861, a four-person board chaired by Captain Samuel Francis Du Pont was formed to study the implementation of the blockade and make recommendations to improve its efficiency. In the board’s report of July 16th 1861, it was recommended that the Atlantic region be divided into northern and southern sectors. On September 18th 1861 the Navy Department decided to implement this division with the dividing line being Cape Fear in North Carolina. The implementation was delayed for a time and it was not until October 12th 1861 that the Navy Department informed Flag Officer Louis Malesherbes Goldsborough that the division of his command would be effective as of the date Flag Officer Samuel Francis Du Pont, who was appointed commander of the southern squadron, departed from Hampton Roads with the expedition to capture Port Royal, South Carolina. Du Pont’s expedition departed on October 29th 1861 and on that date the squadron was divided to form the North Atlantic Blockading Squadron and the South Atlantic Blockading Squadron.
North Atlantic Blockading Squadron
The North Atlantic Blockading Squadron was based at Hampton Roads, Virginia, and was tasked with patrolling the coasts of Virginia and North Carolina with an official range of operation from the Potomac River to Cape Fear in North Carolina. It was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops. It was established when the Atlantic Blockading Squadron was split between the North and South Atlantic Blockading Squadrons on October 29th 1861. After the end of the war, the squadron was merged into the Atlantic Squadron on July 25th 1865.
Louis Malesherbes Goldsborough September 18 1861 – September 4 1862
Samuel Phillips Lee September 5 1862 – October 11 1864
David Dixon Porter October 12 1864 – April 27 1865
William Radford April 28 1865 – July 25 1865
South Atlantic Blockading Squadron
The South Atlantic Blockading Squadron was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops operating between Cape Henry in Virginia to Key West and the southern extremity of Florida. It was created when the Atlantic Blockading Squadron was split between the North and South Atlantic Blockading Squadrons on October 29th 1861. After the end of the war, the squadron was merged into the Atlantic Squadron on July 25 1865.
Samuel Francis Du Pont September 18 1861 – July 5 1863
John Adolphus Dahlgren July 6 1863 – July 25 1865
Gulf Blockading Squadron
The Gulf Blockading Squadron was established on May 6th 1861, with orders to patrol from Key West westwards to the Mexican border. The squadron was the largest force of the US Navy in operation during the War. On January 20th 1862 the Gulf Blockading Squadron was discontinued and its patrol area divided between the East Gulf Blockading Squadron and the West Gulf Blockading Squadron, with the dividing point being east of Pensacola.
William Mervine May 6 1861 – September 21 1861
William McKean September 22 1861 – January 20 1862
East Gulf Blockading Squadron
The East Gulf Blockading Squadron was assigned to patrol the Florida coast from east of Pensacola to Cape Canaveral and was usually the smallest of the Blockading squadrons during the War. It was established on January 20th 1862 when the Gulf Blockading Squadron was split between the East and West
William McKean January 20 1862 – June 3 1862
James L Lardner June 4 1862 – December 8 1862
Theodorus Bailey December 9 1862 – August 6 1864
Theodore P Greene (interim) August 7 1864 – October 11 1864
Cornelius Kinchilo Stribling October 12 1864 – June 12 1865
West Gulf Blockading Squadron
The West Gulf Blockading Squadron was established on January 20th 1862 when the Gulf Blockading Squadron was split between the East and West. It was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops along the western half of the Gulf Coast, from the mouth of the Mississippi to the Rio Grande and south, beyond the border with Mexico.
David Glasgow Farragut January 20 1862 – November 29 1864
James Shedden Palmer November 30 1864 – February 22 1865
Henry Knox Thatcher February 23 1865 – June 12 1865
Operations in Chesapeake Bay
At the outbreak of war, the vulnerability of the capital to naval operations from the Chesapeake Bay along the Potomac River was immediately apparent. As early as April 22nd 1861, Commander James Harmon Ward USN, commanding the receiving ship USS North Carolina at the New York Navy Yard, proposed a plan for the protection of the Chesapeake Bay and capital areas. Ward suggested a “Flying Flotilla” of light draft vessels be formed to operate in the Chesapeake and its tributaries. His superior officer, Captain Samuel Livingston Breese, commandant of the New York Navy Yard, endorsed his plan and it was submitted to Secretary of the Navy Gideon Welles. On April 27th 1861 Welles authorised Breese and Ward to form a “flying flotilla” of light draft vessels to patrol Chesapeake Bay and its tributaries.
The Potomac Flotilla, or “Flying Flotilla” as originally termed, was established to operate in the Chesapeake and its tributaries on April 27th 1861. Commander James Harmon Ward USN assumed command of the “Flying Flotilla” or Potomac Flotilla, acting independently under the direct orders of the Navy Department. The first vessels were acquired for the new “Flying Flotilla” to patrol Chesapeake Bay and its tributaries on May 1st 1861 and on May 16th 1861 Ward set out from the New York Navy Yard with three vessels, the USS Thomas Freeborn, USS Reliance and USS Resolute to form the first active force of the Potomac Flotilla.
On May 20th 1861 Commander James Harmon Ward arrived at the Washington Navy Yard aboard his flagship, the USS Thomas Freeborn to activate the “Flying Flotilla” or Potomac Flotilla. The designation of “Flying Flotilla” was dropped when Ward’s force arrived in the theatre of operations and was referred to by a variety of names, such as Potomac River Flotilla or Potomac Blockade or Flotilla in the Chesapeake. In early August 1861 the commander and the Navy Department began to consistently refer to the command as the Potomac Flotilla.
On June 27th 1861: The “Flying Flotilla” or Potomac Flotilla engaged the Confederate batteries at Mathias Point, Virginia. While he was sighting the bow gun of the USS Thomas Freeborn, the flotilla’s commanding officer, Commander James Harmon Ward was shot and killed. He was the first United States Naval officer to be killed during the war. Commander Stephen Clegg Rowan assumed interim command of the Potomac Flotilla, until July 10th 1861 when Commander Thomas Tingey Craven assumed command of the Potomac Flotilla.
On December 2nd 1861 Lieutenant Abram D Harrell assumed interim command and handed over on December 6th 1861 to Lieutenant Robert Harris Wyman. On July 1st 1862: Lieutenant-Commander Samuel Magaw assumed interim command and Commodore Charles Wilkes assumed command on September 1st 1862. Commodore Andrew Allen Harwood assumed command of the Potomac Flotilla on September 10th 1862. Wilkes commanded for over two years until December 31st 1864 when Commander Foxhall Alexander Parker assumed command of the Potomac Flotilla until July 31st 1865 when the Potomac Flotilla was discontinued and most of its remaining vessels were sent to the Washington Navy Yard to be decommissioned. Over five years of war the Flotilla had employed many vessels, averaging a strength between fifteen and twenty-five vessels.
James Harmon Ward May 20 1861 – June 27 1861
Stephen Clegg Rowan June 27 1861 – July 10 1861
Thomas Tingey Craven July 10 1861 – December 2 1861
Abram D Harrell December 2 1861 – December 6 1861
Robert Harris Wyman December 6 1861 – July 1 1862
Samuel Magaw July 1 1862 – September 1 1862
Charles Wilkes September 1 1862 – September 19 1862
Andrew Allen Harwood September 10 1862 – December 31 1864
Foxhall Alexander Parker December 31 1864 – July 31 1865
The Potomac Flotilla was in frequent action, protecting the capital, raiding the Virginia coasts, supporting operations in Chesapeake Bay and in the tributaries running into it. It also conducted operations in support of the army in the James River in early 1862 and from mid summer 1864 until the end of the war.
Operations on Inland Rivers
Western Gunboat Flotilla and Mississippi River Squadron
All of the vessels available before the war were intended for service along or adjacent to the sea coast, or on the Great Lakes. The Mississippi River flotilla was an entirely different force was required for operations in support of the Army along the extensive inland waterways of the Ohio, Mississippi, Red, Tennessee Cumberland rivers and their tributaries. The Mississippi River Squadron eventually comprised over a hundred vessels of widely varied construction and character. Some were driven by screw-propellers and others by side-wheels or stern-wheels. There were rams, ironclad gunboats, “tinclads,” unarmoured boats of various types and mortar-vessels. The first demand for a river-based flotilla came from the Army and its early organization was directed by the War Department; a US Navy officer was placed in command. The complications arising from this arrangement were solved on October 1st 1862 by the transfer of the force from Army command to the Navy Department. Naval officers were detached to command the various river-based gunboats while gunners and marines were sent to add discipline and expertise to the soldiers-turned-sailors who began the river campaigns.
The first step in the creation of the Mississippi River flotilla was taken in May 1861 by Commander John Rodgers, who purchased three river-steamboats at Cincinnati, named the Conestoga, Lexington and Tyler. They were converted into gun-boats by strengthening their frames, lowering their machinery and protecting their decks by heavy bulwarks. The Union Western Gunboat Flotilla was formed officially on May 16th 1861. It was placed under the command of the Union Army to ensure its support of the armies on western rivers. Commander John Rodgers was the first commander, responsible for the construction and organisation of the fleet.
In August 1861 the War Department made a contract with James B Eads, engineer of the Mississippi jetties, to build seven more gunboats, propelled by a central paddle-wheel and covered with armour two and a half inches thick on the forward end of the casemates and on the sides abreast of the engines. These may be viewed as the first US ironclads, although their plating was light and covered the vessels incompletely. In spite of their defects, these vessels performed service of incalculable importance throughout the war. Each one of the Cairo, Carondelet, Cincinnati, Louisville, Mound City, Pittsburg and St Louis/De Kalb played a significant part in the Mississippi campaigns. Two larger vessels of 1,000 tons displacement, the Benton and the Essex, were more heavily armoured. These and 38 mortar-boats until formed the Mississippi flotilla until the summer of 1862.
Flag Officer Andrew Hull Foote succeeded Rodgers in command of the Western Gunboat Flotilla on August 30th 1861. Foote led the flotilla in operations against Fort Henry, Fort Donelson and Island Number Ten. On May 9th 1862 Foote, who had been wounded, handed over to Flag Officer Charles Henry Davis.
Davis led the command in several actions in support of the army and against Confederate warships at Plum Point Bend and Memphis. In July, he cooperated with ships ascending the Mississippi from New Orleans to attack Vicksburg, Mississippi, but the attack was repelled. In August, he conducted a successful raid up the Yazoo River. He was then made Chief of the Bureau of Navigation and returned to Washington, DC.
With Davis’ departure came a significant change in the command arrangement of the Western Gunboat. The force was officially discontinued, and command transferred from the operational direction of the US Army to the US Navy on October 15th 1862. It was renamed the Mississippi River Squadron and Rear Admiral David Dixon Porter arrived to lead it. Porter’s period of command included decisive operations along the Mississippi against Vicksburg, He also commanded the naval forces in the unsuccessful Red River campaign.
In late summer 1864 Porter was selected to command operations against Fort Fisher in North Carolina. Porter exchanged places with Rear Admiral Samuel Phillips Lee, who came from the North Atlantic Blockading Squadron to the Mississippi. From July 31 1864 Captain Alexander Moseley Pennock exercised interim command of the Mississippi River Squadron until Lee arrived on November 1st 1864. Lee remained in command through the final operations until the squadron was discontinued on August 14th 1865.
During the following years important additions were made to the Mississippi flotilla. These were of two classes, light-draft gunboats and ironclads. The light-draft ships were small stern-wheel boats armed with howitzers, intended for scouting and light operations. They took part in fighting in the shoal waters of the Yazoo and Red River. Drawing less than two feet of water they could go almost anywhere; their howitzer batteries and light, bullet-proof plating made them efficient vessels for clearing the riverbanks of enemy field guns and sharpshooters. Though insufficient to resist a heavy shell, this plating was bullet-proof and would withstand the shot from a light field-piece, unless the projectile chanced to find a vulnerable spot, such as an open port-hole. Their armour of less than one-inch thickness earned them the colloquial name of “tinclads.” They included the Forest Rose, Juliet, Marmora, Rattler, Romeo and Signal and the tiny Cricket, all of which took part in the fighting.
The second class of new acquisitions were more heavily armoured vessels, but they were not necessarily more efficient. The Tuscumbia, Indianola and Chillicothe were side-wheel casemate ironclads, carrying thicker plating than earlier boats and a more formidable armament. Their poor and hasty workmanship rendered them unequal to rigorous service. The two large steamers Lafayette and Choctaw, each displacing 1,000 tons, were more efficient. They were well-built side-wheelers altered into casemate ironclads and fitted with rams. Later, three turreted ironclads of light draft, the Osage, Ozark and Neosho were added to the flotilla. These ships, together with a number of captured gunboats such as the Eastport and a few wooden steamers of various size and miscellaneous description, conducted operations from the autumn of 1862 onwards.
In addition to these vessels, a fleet of steam-driven rams was also built for service on the western rivers. This fleet was the conception of Colonel Charles Ellet Jr who had advocated the value of the iron-prowed ram as a naval weapon before the war. Ellet bought nine river-boats which he strengthened and altered into rams of his own design. They were named the Queen of the West, Monarch, Samson, Lioness, Switzerland, Lancaster, Minao, T D Horner and Dick Fulton. They were hastily produced but performed valuable service during the river operations, although their ramming exploits were few.
The Mississippi River Squadron operated on the western rivers during the American Civil War. It was initially created as a part of the Union Army, although it was commanded by naval officers, and was first known as the Western Gunboat Flotilla and sometimes as the Mississippi Flotilla. It received its final designation when it was transferred to the Union Navy at the beginning of October 1862. The squadron was created on May 16 1861 and was controlled by the Union Army until September 30 1862. Commander John Rodgers was the first commander of the squadron and was responsible for the construction and organization of the fleet. Flag Officer Andrew Hull Foote relieved Rodgers and encouraged the army commander in the west, Major-General Henry W Halleck, to authorise an expedition down the Tennessee River against Fort Henry. Operating in conjunction with Ulysses S Grant’s Army of the District of Cairo, Foote subdued Fort Henry before Grant’s troops could take their positions. Foote led the squadron in the attack on Fort Donelson and then joined with Major-General John Pope’s Army of the Mississippi for a joint attack on Island No 10 on the Mississippi River. Charles H Davis relieved Foote and proceeded to take Fort Pillow on the Mississippi. The US Ram Fleet commanded by Colonel Charles Ellet accompanied the squadron during the Battle of Memphis. After the capture of Memphis, the squadron was transferred to the control of the US Navy. The transfer included the Ram Fleet, by then reconstituted as the Mississippi Marine Brigade. Davis aided Grant’s first and unsuccessful campaign against Vicksburg. Rear Admiral David Dixon Porter relieved Davis in command and led the squadron at Arkansas Post and during the successful Vicksburg Campaign and siege of the city. Porter led the squadron during the disastrous Red River Campaign and when the waters of the river dropped the fleet was almost lost. The engineering abilities of Colonel Joseph Bailey who supervised the construction of Bailey’s Dam helped save the fleet. Command temporarily passed to Alexander Pennock before Samuel Powhatan Lee assumed command. Lee was in command until the squadron was discontinued on August 14 1865.
John Rodgers, 16 May 1861 to 30 August 1861
Andrew Hull Foote, 30 August 1861 to 9 May 1862
Charles Henry Davis, 9 May 1862 to 15 October 1862
David Dixon Porter, 15 October 1862 to 31 July 1864
Alexander Moseley Pennock, 31 July 1864 to 1 November 1864 (temporary)
Samuel Powhatan Lee, 1 November 1864 to 14 August 1865
The US Ram Fleet and Mississippi Marine Brigade
The US Ram Fleet was an unusual force created to support operations along the western rivers. It was never part of the Mississippi River Squadron and its status was often anomalous.
In March 1862, the US Army authorised the noted civil engineer Charles Rivers Ellet to establish a flotilla of steam-powered ram ships for employment on the Western Rivers. Ellet converted several powerful river towboats, heavily reinforcing their hulls for ramming. These ships had light protection for their boilers, engines and upper works and the upper works were protected with wood and cotton bales. They were not originally equipped with artillery, but later most were fitted with guns. Colonel Ellet led his force at Memphis on June 6th 1862 but died several days later of a wound received at that action. After his death, his younger brother Alfred Washington Ellet took command of the US Ram Fleet.
The Ram Fleet remained under the command of the US Army even after the transfer of the Western Gunboat Flotilla to US Navy command on October 15th 1862. It continued to operate independently. To counter the growing depredations of guerrillas, A W Ellet proposed forming a special unit of soldiers to protect the Mississippi Valley and tributaries. The War Department approved the idea and the Mississippi Marine Brigade was formed on November 1st 1862, with Ellet in command as Brigadier-General. The brigade composed a battalion of infantry, a battalion of cavalry and a light battery. The Ram Fleet was assigned to transport and support the brigade and by early 1863 the two commands became synonymous as the Mississippi Marine Brigade.
The Mississippi Marine Brigade reported directly to the War Department and there was continual uncertainty of its authority. It participated in several operations, but its reputation declined as it did not coordinate its operations with the army or navy and gained a reputation for growing indiscipline and even lawlessness. Reckless and unauthorised operations resulted in the loss the USS Queen of the West and USS Switzerland during 1863. The Mississippi Marine Brigade assisted at the siege of Vicksburg and in the Red River campaign but remained beyond the jurisdiction of local commanders. The War Department finally disbanded the command in August 1864.
Operations on Lake Erie
While the war was being conducted along and across the Confederate borders, the Union was also alert to threats from the British colony of Canada. The US Navy had withdrawn from the Great Lakes after the War of 1812. The relationship between the USA and the British in Canada were tense during the 1830s and worsened when it was learned that British warships were being built in Canada. The HMS Minos was launched in 1840 and was reported to be an invulnerable ironclad ship. It was in fact a wooden paddle steamer and it was out of service by 1852. In response, the US Navy launched an iron ship on Lake Erie, to provide security and also to test the practicality and usefulness of iron warships. The iron-hulled steamer USS Michigan was launched on Lake Erie on 5 December 1843. Great Britain and France were experimenting already with iron-hulled ships, but the USS Michigan was the first of its kind in the USA.
The USS Michigan cruised the Great Lakes unhindered and, after the Draft Riots in New York City in 1863, it was called upon to offer an admonitory presence in Detroit and Buffalo.
The Confederacy considered several plans to attack from Canada several times. In 1863 Lieutenant William Henry Murdaugh drew up a scheme for a small group of naval officers to travel to Canada, purchase a Canadian-crewed steamer, and attack the USS Michigan on Lake Erie. The Confederates aimed to control the locks and shipping on the Great Lakes, but the ambitious plan was not approved.
On 19 September 1864 twenty Confederate supporters disguised as passengers boarded the American steamer Philo Parsons, and seized command of the ship later near Kelly’s Island. Acting Master John Yates Beall and his men were on a mission to liberate the Confederate prisoners at Johnson’s Island. Their plan also involved the capture of the USS Michigan, which was guarding a Union Prisoner of War Camp in Sandusky Bay, Ohio, and then to conduct raids on commerce and attacks on Great Lakes cities. Confederate agent Charles H Cole was operating among the officers of the USS Michigan, but his deception was uncovered, and he was arrested When the Philo Parsons and its pro-Confederate crew approached Johnson’s Island, Cole was unable to send the agreed signals to Beall. The mission was abandoned, and the conspirators retreated to Sandwich (Windsor), Canada, where they stripped and burned the vessel. The USS Michigan continued to patrol the Great Lakes for decades after the Civil War and was renamed USS Wolverine in 1905.
Evolution of Union Ironclads
The advantages of light armour-plating for warships had been demonstrated by the French floating batteries Devastation, Lave and Tonnante during the Crimean war in 1855. These vessels were protected by 4 ½ -inch plates, and the experiment was deemed so conclusive in Europe that both France and Great Britain had already constructed new warships encased in armour. However, the value and practicability of these first three experimental ironclad warships in battle was in doubt for the particular needs of the US Navy. The Navy Department at first moved cautiously in adopting ironclads. On July 4th 1861 Gideon Welles, US Secretary of the Navy, drew attention to the subject:
“Much attention has been given within the last few years to the subject of floating batteries, or iron-clad steamers. Other governments, and particularly France and England, have made it a special object in connection with naval improvements; and the ingenuity and inventive faculties of our own countrymen have also been stimulated by recent occurrences toward the construction of this class of vessel….”
On 3rd August 1861 the US Congress passed an act authorizing the Secretary to appoint a board of naval officers to investigate the subject of ironclad warships, appropriating $1,500,000 for the work. On 8th 1861 August the board was appointed, composed of Commodores Smith and Paulding and Commander Davis. The board remarked that it approached the subject “with diffidence, having no experience, and but scanty knowledge in this branch of naval architecture.” This was true and although they knew that the Confederates were already experimenting with an ironclad ship at Norfolk. The board six weeks to submit its recommendations and its conclusions were non-committal:
“Opinions differ amongst naval and scientific men as to the policy of adopting the iron armature for ships-of-war. For coast and harbour defence they are undoubtedly formidable adjuncts to fortifications on land. As cruising vessels, however, we are sceptical as to their advantages and ultimate adoption. But whilst other nations are endeavouring to perfect them, we must not remain idle…. We, however, do not hesitate to express the opinion, notwithstanding all we have heard or seen written on the subject, that no ship or floating battery, however heavily she may be plated, can cope successfully with a properly constructed fortification of masonry.”
In his report to Congress in December 1861, the US Secretary of the Navy stated: “The subject of iron armature for ships is one of great general interest, not only to the navy and country, but is engaging the attention of the civilized world.”
The board selected three plans, offered respectively by Bushnell & Co of New Haven, Merrick, & Sons of Philadelphia and John Ericsson of New York. These resulted in the construction of the Galena, the New Ironsides and the Monitor. Heavily armoured with iron and wood, the Galena and the New Ironsides were adapted to the mounting of heavy guns and no wooden vessel could survive against them, broadside to broadside. The plans were sound, but the Galena failed to fulfil expectations and it was not duplicated. The New Ironsides proved an efficient vessel within a limited sphere of action but again only one example of the type was built. The most unconventional ship, the Monitor, proved to be such a successful design that hardly any other model was adopted afterwards. It included many innovations in naval construction and the prototype was built at Continental Iron Works in New York. The Monitor was 172-feet in length, over 41-feet in beam and presented a free-board of only 18 inches above the water. The main feature of the Monitor was its revolving turret, 21-feet in diameter and 9-feet high mounted almost amidships. There was an exceptionally low freeboard and a projecting overhand. The ship presented a very small target, and the engines, battery, screw, rudder, anchor and crew were all well protected. It was resistant to attack by rams and gunfire, but the low freeboard had the distinct disadvantage that even a small influx of water could sink the ship. The idea of mounting guns in a revolving circular turret had been suggested at various times but had never before been applied successfully. In 1842 Timby had proposed a system of coastal fortification based on this idea, but the plan was defective and rejected. In 1854 Ericsson submitted to Napoleon III of France a design for an ironclad battery with a hemispherical turret. In 1843 Captain Cowper Coles RN suggested a vessel in the form of a raft with a stationary shield protecting the guns, and in 1859 he improved this design by adding a revolving cupola. But it was left to Ericsson to develop an effective to construct a navigable and seemingly impregnable ironclad fitted with a revolving gun turret.
Once the Navy Department understood Ericsson’s design, it was adopted immediately and enthusiastically. According to Ericsson,
“The Committee of Naval Commanders… occupied me less than two hours in explaining my new system. In about two hours more the committee had come to a decision. After their favourable report had been [made] to the Secretary I was called into his office, where I was detained less than five minutes. In order not to lose any time, the Secretary ordered me to ‘go ahead at once.’ Consequently, while the clerks of the department were engaged in drawing up the formal contract, the iron which now forms the keel-plate of the Monitor was drawn through the rolling-mill.”
The contract for the Monitor was signed on 4th October 1861. The energy of the contractors pushed the work to completion with exemplary speed. But the new ironclad was not ready in time to prevent the raid of the Confederate Merrimac (renamed the Virginia) in Hampton Roads on 8th March 1862 and the sinking of the Congress and the Cumberland. The arrival of the Monitor saved the rest of the wooden fleet from the threat of a similar fate.
The US Navy possessed five sister ships of the Confederate Merrimac/Virginia and any of these could have been armoured efficiently in less time and at less expense than that expended by the Confederates. While the Navy Department hesitated for six months in adapting their existing ships, the more innovative Monitor filled the gap and that improved design made it unnecessary to adapt them.
In addition to the three ironclad vessels selected by the board of 1861, nearly sixty ironclads were built or projected during the war. All were of the Monitor type except for three: the huge ram Dunderberg which was sold to the French Government and renamed the Rochambeau, the Keokuk which was sunk after the battle of April 7th 1863 and the converted frigate Roanoke. Of the fourteen double-turreted monitors (including the Puritan, the Onondaga, the Kalamazoo class, the Monadnock class and the Winnebago class), only six were finished in time to take an active part in the war. The single-turreted monitors that saw most service were of the Passaic class, mostly stationed in the South Atlantic Squadron. Besides these there were the Dictator, nine vessels of the Canonicus class and twenty lighter-draft monitors. The latter group were never used as faulty calculations for their displacement meant that they could not float with both guns and coal loaded.
With the introduction of the ironclad and continual improvements in their armour, the guns of the navy also changed in weight and pattern. At the beginning of the war, the 32-pounder and the 8-inch were among the most powerful guns in use, although some steam vessels were equipped with 11-inch Dahlgren guns. By the end of the war, the 11-inch Dahlgren gun had been superseded and calibres had risen to 15-inch, 18-inch and even 20-inch guns, although the latter never saw active service. Rifled artillery increasingly replaced the conventional smoothbore guns, giving added range, and accuracy to naval guns and transforming the nature of naval warfare. For centuries, wooden-walled sailing vessels had closed to short range to pound each other with massed batteries, but now technology permitted the fights to be conducted at greater and greater distances. The concept of ironclads being used as invincible rams to smash into enemy ships was popular and many successful ramming attacks were conducted. However, the tactic was abandoned quickly as weapons and armour made it unfeasible.