The Tennessee-class cruisers were four armored cruisers built for the United States Navy between 1903 and 1906. Their main armament of four guns in twin turrets was the heaviest carried by any American armored cruiser. Their armor was thinner than that of the six s which immediately preceded them, a controversial but inevitable decision due to newly imposed congressional restraints on tonnage for armored cruisers and the need for them to be able to steam at . However, the fact their armor covered a wider area of the ship than in the Pennsylvanias and their increased firepower caused them to be seen by the Navy as an improvement.
The Tennessees were the largest and last American armored cruisers built, a response to foreign developments and the changing notion of the armored cruiser from fast scout, convoy escort and commerce raider to auxiliary capital ship in a battle line, despite its thin armor protection compared to that of battleships. The Battle of Tsushima in 1905 was seen to validate this concept. While they were being built, questions remained in U.S. naval circles over whether they possessed enough speed, armament or armor to perform their intended duties adequately. They were generally considered armed and protected strongly enough to combat an enemy armored cruiser successfully. Even so, it was generally conceded that with this class a limit had been reached and that the modern armored cruiser no longer exemplified the logical principles of attack and defense in warship design, which meant using the most efficient weapon to its desired end. The appearance of the British s, with their greater speed and firepower, ensured their obsolescence as fighting units.
All four ships in this class were given the hull classification symbol CA (armored cruiser) when the Navy adopted that system in 1920, and renamed by then so their original names could be used for new battleships. , renamed Memphis, was wrecked by a tsunami while at anchor in Santo Domingo harbor in 1916. The other three ships served in World War I. The Navy considered modernization in 1922 and 1928 to upgrade their speed and fighting capability but this did not materialize. , renamed Charlotte, and , renamed Missoula, were scrapped under the terms of the London Naval Treaty, which set an aggregate tonnage limit for the Navy's cruisers, and the new heavy cruisers of the and subsequent classes were entering service. , renamed Seattle, was reclassified in 1931 and served as a receiving ship and floating barracks until scrapped in 1946.
Background
Cruiser race; Japanese rumblings
A race to build armored cruisers to protect maritime trade, attack commerce and maintain a presence at foreign stations had been taking place since the 1890s, with ships built with larger guns and an arrangement of guns and armor similar, at least in overall design if not in degree, to that of battleships. The Royal Navy had pursued an extended period of armored cruiser construction as part of the arms race between it and the Imperial German Navy and to have enough ships to safeguard the vast British Empire. Beginning with the in 1898, it had laid down or was planning seven classes of armored cruisers, a total of 35 ships. The last of these, the , would displace 14,600 tons, be capable of and be armed with four and 10 guns. This would give Great Britain the largest armored cruiser force in the world. France was building a series of increasingly large armored cruisers for scouting and commercial warfare, beginning with the 11,000-ton in 1896, protected with a belt and armed with and guns, and culminating with the 14,000-ton , slightly faster at 23 knots, armed with 14 guns and armored with up to on their belts, almost on their decks and on their turrets. Germany, as part of its Second Naval Law, began a series of 14 armored cruisers envisioned for use on overseas stations. Between 1897 and 1906 they would lay down eight, the initial two armed with guns, the other six with more modern . The final pair, and , would displace 12,781 tons, steam at 23.5 knots, carry of belt and of deck armor and carry eight 8.2 inch guns.
Then there was Japan. Its naval build-up following the end of the First Sino-Japanese War in 1895 and its forced return of the Liaotung peninsula to China under pressure from Russia, Germany and France (in what became known as the "Triple Intervention") had at its core a "Six-Six Program" of six battleships and six (eventually eight) armored cruisers comparable to the British Cressy class. The followed the basic pattern for these cruisers—on a displacement, she carried four and twelve guns, was protected by a main belt, armored deck and turret armor and steamed at . United States President Theodore Roosevelt, while impressed with Japan's success in the war and its modernization overall, considered its actions a threat to American interests in the Pacific region. This in turn had motivated him to maintain a "controlling voice" in the Philippines after the Philippine–American War ended in 1902 and would encourage him to send the Great White Fleet on its worldwide voyage in 1907. (Unfortunately, the visit of the fleet would inspire Japan to step up its building program still further.) Japan's 1905 victory in the Russo-Japanese War would usher its entrance as a world power and begin a rivalry with the United States over dominance in the Pacific. As Roosevelt would surmise during that conflict in a letter to British diplomat Cecil Spring Rice, "The Japs interest me and I like them. I am perfectly well aware that if they win out it may possibly mean a struggle between them and us in the future."
To keep up with these developments and better protect the large sea areas the U.S. had recently won in the Spanish–American War, the U.S. Navy had built six 13,680-ton Pennsylvania-class cruisers. Armed with four and 14 guns, covered with of belt armor and with a top speed of 22 knots, they were considerably bigger than and which preceded them and improved in overall protection. However, the Navy considered the armored area of these ships restricted and the caliber of their heavy guns small compared to their displacement. This did not stop the Navy's Bureau of Construction and Repair (C&R) from requesting funds from Congress for two additional units as part of the 1901 naval building program. When Congress did not approve funding for these ships, this obligated the Secretary of the Navy under law to order a new study of capital ship and armored cruiser designs that Congress might approve. A smaller, 11,000-ton design with thinner armor than the Pennsylvanias was favored by the Board's new Chief Constructor, F. T. Bowles, who considered the Pennsylvanias "indefensible on account of their size." However, reducing the size of any new warships was considered unacceptable politically, as Congress had already opposed the growth in size and cost of vessels recently commissioned. Also, Rear Admiral R.B. Bradford of the Bureau of Equipment and Recruiting, who had supported the building of the Pennsylvanias, wanted to keep the new ships as homogeneous in size as possible to the earlier ones and at least comparable to them in fighting strength.
Development Several design issues on the new cruisers had to be worked out by C&R before a proposed design could be finalized. Bowles was concerned over what he considered inadequate protection in the Pennsylvanias, especially the thin deck armor near the main magazines. British designs placed these magazines well below the ship's waterline and far back from her sides but tended to be much smaller than in US designs. Since US cruisers generally carried heavier armament than their British counterparts, this necessitated magazines with greater volume to ensure adequate ammunition. In his 14,500-ton proposed design labeled "F," Bowles extended the casemate armor to include the turrets and increased the ship's beam slightly to compensate for the added weight. He also wanted to make the side armor one inch thinner than in the Pennsylvanias and concentrate the 6-inch guns at the ends of the ships to increase the areas covered by their protection.
There was also the question of whether any new armament should be included in the proposed cruiser. New weapons under consideration included a heavy gun and a secondary gun. The 7-inch gun was especially scrutinized since its shell was the heaviest that could be handled manually. Proposed design "G" included both these weapons; however, Bradford suspected that, due to the issue of weight, the 8-inch cannons used in the Pennsylvanias might be more practical as main armament. The weight of four 10-inch and 16 7-inch guns was such that the armor over the casemates would have to be reduced to for flat surfaces and by for the outside slopes. Proposed design "H," armed with four 10-inch and 16 guns, offered better protection, with of casemate armor extended from top to bottom between the two turrets to protect ammunition for the anti-torpedo boat guns. This was the design submitted to the Secretary of the Navy on 31 July 1901 with a request to include two additional 3-inch guns and greater isolation of the 6-inch battery.
Meanwhile, Congress had become concerned about the growing size of new Navy ships of all ratings and set a firm limit of 14,500 tons, the same as the Pennsylvanias, for armored cruiser project to be considered for the 1902 naval building program. This limit paralleled one that Congress had previously set for battleships. The estimated weight for proposed design "H" was 14,700 tons. Also, Engineer in Chief George Wallace Melville had requested engines for these ships with 2000 more indicated horsepower than the Pennsylvanias to compensate for 1500 tons of accumulated weight during the design process. The added horsepower would ensure a top speed of 22 knots, the same as the Pennsylvania class. The tonnage limitation may have been expected since means to save weight on the new design were already being sought in the fall of 1901. At that time, Melville was asked about reducing boiler weight, to which he refused, claiming it was impossible for him to install reliable machinery of 25,000 horsepower for the same amount of weight as he had been allocated for 23,000 horsepower in the Pennsylvanias.
The issue of reducing engineering weight reemerged when Bowles asked for 200 extra tons to increase deck armor. Even with the decrease, he argued, the ships would still be able to make 22 knots. Bradford sided with Bowles but Melville claimed he could save only 50 tons; the other 140 tons could be saved by reducing the amount of coal the ships carried on trials from 900 to 750 tons. This, Bowles replied, would make the new cruisers a "fake design." Nor was it entirely clear whether they really needed 25,000 horsepower to attain their designed speed. Model testing, then new, was apparently something in which Melville did not believe and none of the Pennsylvanias had yet run trials. Melville cited British cruisers of the same size as the new design, which used 30,000 horsepower to steam at 24 knots. After heated discussion the board agreed on 23,000 indicated horsepower and a design speed of 22 knots.
The first pair of these cruisers, Tennessee and Washington, were approved by Congress under the 1902 Naval Building Program. The other pair, North Carolina and Montana, were approved in 1904.
Design