Two South Carolina-class battleships, also known as the Michigan class, were built for the United States Navy in the early twentieth century. Named and , they were the first American dreadnoughts—powerful warships whose capabilities far outstripped those of the world's older battleships.

At the turn of the twentieth century, the prevailing theory of naval combat was that battles would continue to be fought at relatively close range using many small, fast-firing guns. As such, each of the ships in the United States' previous s carried many medium-sized weapons alongside four large guns. This paradigm was soon to be subverted, as American naval theorists proposed that a ship mounting a homogeneous battery of large guns would be more effective in battle.

As these ideas began to enjoy wider acceptance, the US Congress authorized the country's navy to construct two small battleships. This displacement was roughly the same size as the Connecticut class and at least smaller than foreign equivalents. A solution was found in an ambitious design drawn up by Rear Admiral Washington L. Capps, the chief of the navy's Bureau of Construction and Repair; it traded speed for heavy armament and relatively thick armor, both of which were favored by naval theorists of the time.

With their superfiring main armament, press accounts billed South Carolina and Michigan, along with the British , as heralding a new epoch in warship design. All three, however, were soon surpassed by ever-larger and stronger super-dreadnoughts. The class's low top speed of about , as compared to the standard of later American battleships, relegated them to serving with older, obsolete battleships during the First World War. After the end of the conflict and the signing of the Washington Naval Treaty, both South Carolinas were scrapped.

Background

In 1901, the US Navy's battleship designs reflected the prevailing theory of naval combat: battles would begin at long distances before closing the range for knockout blows. In the latter stage, shorter-range, faster-firing guns would prove most useful. Following this philosophy, the premier battleship class then under construction—the —carried four large , eight , and twelve guns, an armament slightly heavier than typical foreign battleships of the time.Campbell, "United States of America: 'The New Navy', 1883–1905," 137–38, 143; Friedman, US Battleships, 52.

The Naval Institute's Proceedings magazine devoted space in two of its 1902 issues to possible improvements in battleship design. The first article was authored by Lieutenant Matt H. Signor, who argued for a ship with and /40 caliber guns in four triple turrets. The secondary battery would be composed of /60 guns. This paper provoked enough thought that Proceedings published comments on the story from Captain William M. Folger, Professor P. R. Alger, and naval constructor David W. Taylor—the latter an up-and-coming officer and future head of the Bureau of Construction and Repair (C&R). These comments expressed doubt that the proposed vessel could be codified into a feasible design, but they praised his thoughts as a step in the right direction. Alger believed that Signor was on the right track in suggesting larger armament, though he thought that triple turrets would be unworkable and eight 12-inch guns in four twin turrets would be a much more realistic arrangement. With this, naval historian Norman Friedman believes that Alger made one of the "earliest serious proposals for a homogeneous big-gun battery."Friedman, US Battleships, 51; Signor, "A New Type of Battleship"; Folger, Alger, Taylor, "Discussion".

The suggestion leading directly to the South Carolina class came from Homer Poundstone, a Lieutenant Commander in the Navy, who became the principal proponent of an American all-big-gun design. In a December 1902 paper written for President Theodore Roosevelt, he argued for greatly increasing the size of current battleships, although he also supported retaining mixed main batteries.Friedman, US Battleships, 52. However, by the March and June 1903 editions of Proceedings, Poundstone began advocating for an all-big-gun arrangement, featuring twelve guns mounted on a ship. In October of the same year, the Italian naval architect Vittorio Cuniberti presented a similar idea in an article for Jane's Fighting Ships entitled "An Ideal Battleship for the British Navy". He argued in favor of a ship with twelve 12-inch guns on a slightly larger displacement than the battleships in service at the time, . He believed that the higher weight would allow 12 inches of armor and machinery capable of propelling the ship at . Poundstone used what he believed to be the great popularity for this idea among Europeans to justify the all-big-gun design.Friedman, US Battleships, 52; Cuniberti, "An Ideal Battleship"; Friedman, "South Carolina Sisters," Poundstone, "Size of Battleships for US Navy," 161–74; Poundstone, "Proposed Armament," 377–411.

In 1903, Poundstone's designs began receiving attention from American naval authorities. After being refined by Washington Irving Chambers, Poundstone's work was brought to the Naval War College, where it was tested in war games during the 1903 Newport Conference. The results indicated that a theoretical battleship that dispensed with the intermediate 8- and 7-inch armament and was armed with only twelve 11- or 12-inch guns, all able to fire on a single broadside, was worth three of the battleships then in service. According to the men who conducted the tests, the main reasoning for the finding was that the measure of effective gun ranges was directly related to the maximum length of an enemy's torpedo range. At this time, the latter was roughly ; at that distance, the 7- and 8-inch guns common to American intermediate batteries would not be able to penetrate the armor of enemy battleships. Worse still, it was certain that—as the United States was developing a torpedo—gun range would have to rise in the near future, making the intermediate guns even less useful. However, a homogeneous main battery of 11- or 12-inch guns would be able to penetrate the armor and have sufficient explosive power to disable an enemy capital ship, and adding as many guns as possible would provide a strong defense against torpedo-carrying but unarmored destroyers.Friedman, US Battleships, 53; Friedman, "South Carolina Sisters".

Design

Faced with this evidence, the General Board sent a formal request in October 1903 to C&R, asking it to draw up plans for a battleship including these characteristics. No progress had been made by 26 January 1904, when the General Board asked C&R for a design including four 12-inch guns, eight 10-inch or larger guns, and no intermediate armament beyond 3-inch anti-destroyer guns. The move to only 10-inch weaponry was the result of doubt among naval authorities that heavier guns could physically be mounted on a ship's broadside. No action was taken on this request until September, when C&R began planning a ship with four 12-inch guns in dual turrets along with eight dual 10-inch or four single 12-inch guns.

Meanwhile, the Naval War College played three battleship designs against each other at its 1904 Newport Conference: the ships that were built following the 1903 conference; the new C&R design from September; and the latest battleships under construction, the Connecticut class. The 7- and 8-inch guns, and even the 10-inch guns, were demonstrated again to be unsatisfactory; even when hitting a battleship at the ideal angle of ° to its belt, they failed to pierce beyond 12 inches of Krupp armor—not enough to counter enemy capital ships. Speed calculations were also performed which demonstrated that even a advantage over an enemy fleet would be inconsequential in the final outcome of almost all naval battles because the slower ships could stay within range by turning on a tighter radius.Friedman, US Battleships, 53–54.

Within the naval bureaus, however, there was still much resistance. In mid-to-late 1904, Poundstone continued to lobby the General Board while C&R protested that the final determinant in a naval battle would be the light guns—and in any case such a large uniform battery was not feasible. Poundstone replied with a design of his own creation, which he called USS Possible and fit twelve 11-inch guns on a ship that displaced 19,330 long tons. With support from Lieutenant Commander William Sims, who was able to cite the increasingly accurate long-gunnery of the Navy, and interest shown in the project by President Roosevelt, the bureaucratic stalling ended.Friedman, US Battleships, 54–55.

On 3 March 1905, Congress passed a bill that authorized the Navy to construct two new battleships to be named after the states of South Carolina and Michigan. The maximum tonnage limit was set at 16,000 long tons, the same weight as the mixed-battery Connecticut class of two years prior, in an attempt to stem the rising displacement—and accompanying costs—of the Navy's new capital ships.Friedman, US Battleships, 55; Friedman, "South Carolina Sisters". The provision was met with a mixed reception from naval designers. Some, including retired Admiral of the Navy George Dewey, thought the limit should have been set at the minimum standard of foreign battleships, or around . Others believed adding a significant amount of speed or firepower—something one would expect with an increase in tonnage—would require much more than 18,000 tons, and argued that the increase in size would buy nothing more than an increased target profile."Dispute over Battleships," New York Times, 16 October 1905, 6.

The Constructor of the Navy, Rear Admiral Washington L. Capps, devised an ambitious design that packed powerful armament and thick armor onto the small hull. He believed that future naval battles would involve fleets rather than single-ship actions, and so while the wing turrets so common in European designs were useful in the latter role for putting a maximum amount of firepower in any given direction, they were less so when operating as part of a line of battle. From this, Capps theorized that the principal concern of battleships was how much shell weight they could fire per broadside. The arrangement of superfiring turrets placed on the centerline would allow the hull to be as short as possible while still having the most powerful broadside possible. A ship with its main battery placed along the center of the ship can focus the same amount of fire to port (left) or starboard (right) during a broadside. In contrast, wing turrets had significant shortcomings: their location on either side of a ship's superstructure led to smaller total broadsides, and the extreme weight placed on the sides of the ships led to torsional stress and rolling inertia.Friedman, Battleship Design, 134.

As the additional main battery turrets with their associated magazines used a great amount of space within each already-limited ship, Capps was forced to economize in other ways to stay within the tonnage limit. Machinery had to be built smaller than normal to fit in the space between the fore and aft magazines, both of which were larger than usual. Boiler rooms were moved inboard to make room for torpedo protection. The biggest drawback was in propulsion: there was no room for engines that could provide the same amount of power as on previous battleships. Capps suggested cutting down the number of boilers by one-third to make room; it may have been at this point that he considered turbine propulsion. All the Bureau of Engineering could offer in response was more compact boiler rooms by eliminating centerline bulkheads.Breyer, Battleships, 196; Friedman, US Battleships, 57.