[Footnote 1: Custance, The Ship of the Line in Battle, p. 9.]
In 1851 Minié rifles supplanted in the British army the old smoothbore musket or "Brown Bess," with which at ranges above 200 yards it was difficult to hit a target 11 feet square. This change led quickly to the rifling of heavy ordnance as well. The first Armstrong rifles of 1858—named after their inventor, Sir William Armstrong, head of the Royal Gun Factory at Woolwich—included guns up to 7-inch diameter of bore. The American navy, however, depended chiefly on smoothbores throughout the Civil War.
Breech-loading, which had been used centuries earlier, came in again with these first rifles, but after 1865 the British navy went back to muzzle-loading and stuck to it persistently for the next 15 years. By that time the breech-loading mechanism had been simplified, and its adoption became necessary to secure greater length of gun barrel, increased rapidity of fire, and better protection for gun-crews. About 1880 quick-fire guns of from 3 to 6 inches, firing 12 or 15 shots a minute, were mounted in secondary batteries.
As already suggested, the necessity for armor arose from the smashing and splintering effect of shell against wooden targets and the penetrating power of rifled guns. To attack Russian forts in the Crimea, the French navy in 1855 built three steam-driven floating batteries, the Tonnant, Lave, and Dévastation, each protected by 4.3-inch plates and mounting 8 56-lb. guns. In the reduction of the Kinburn batteries, in October of the same year, these boats suffered little, but were helped out by an overwhelming fire from wooden ships, 630 guns against 81 in the forts.
The French armored ship Gloire of 1859 caused England serious worry about her naval supremacy, and led at once to H. M. S. Warrior, like the Gloire, full rigged with auxiliary steam. The Warrior's 4.5-inch armor, extending from 6 feet below the waterline to 16 feet above and covering about 42 per cent of the visible target, was proof against the weapons of the time. At this initial stage in armored construction, naval experts turned with intense interest to watch the work of ironclads against ships and forts in the American Civil War.
The naval activities of this war are too manifold to follow in detail. For four years the Union navy was kept constantly occupied with the tasks of blockading over 3000 miles of coast-line, running down enemy commerce destroyers, cooperating with the army in the capture of coast strongholds, and opening the Mississippi and other waterways leading into the heart of the Confederacy. To make the blockade effective and cut off the South from the rest of the world, the Federal Government unhesitatingly applied the doctrine of "continuous voyage," seizing and condemning neutral ships even when bound from England to Bermuda or the Bahamas, if their cargo was ultimately destined for Southern ports. The doctrine was declared inapplicable when the last leg of the journey was by land,[1] doubtless because there was little danger of heavy traffic across the Mexican frontier. Blockade runners continued to pour goods into the South until the fall of Fort Fisher in 1865; but as the blockade became more stringent, it crippled the finances of the Confederacy, shut out foodstuffs and munitions, and shortened, if it did not even have a decisive effect in winning the war.
[Footnote 1: Peterhoff Case, 1866 (5 Wall, 28).]
To meet these measures the South was at first practically without naval resources, and had to turn at once to new methods of war. Its first move was to convert the steam frigate Merrimac, captured half-burned with the Norfolk Navy Yard, into an ironclad ram. A casemate of 4 inches of iron over 22 inches of wood, sloping 35 degrees from the vertical, was extended over 178 feet, or about two-thirds of her hull. Beyond this structure the decks were awash. The Merrimac had an armament of 6 smoothbores and 4 rifles, two of the latter being pivot-guns at bow and stern, and a 1500-lb. cast-iron beak or ram. With her heavy load of guns and armor she drew 22 feet aft and could work up a speed of barely 5 knots.
Faced with this danger, the North hurriedly adopted Ericsson's plan for the Monitor,[2] which was contracted for on October 4, 1861, and launched after 100 days. Old marlin-spike seamen pooh-poohed this "cheesebox on a raft." As a naval officer said, it might properly be worshiped by its designer, for it was an image of nothing in the heavens above, or the earth beneath, or the waters under the earth. It consisted of a revolving turret with 8-inch armor and two 11-inch smoothbore guns, set on a raft-like structure 142 feet in length by 41-1/2 feet in beam, projecting at bow, stern, and sides beyond a flat-bottomed lower hull. Though unseaworthy, the Monitor maneuvered quickly and drew only 10-1/2 feet. She was first ordered to the Gulf, but on March 6 this destination was suddenly changed to the Chesapeake.