The Pennsylvania class of six armored cruisers served in the United States Navy from 1905 to 1927. All six were renamed for cities 1912–1920, to make the state names available for the new battleships beginning with the s. All of these served during World War I, with California (then San Diego) being the only ship of the class to be lost. The remaining five armored cruisers were scrapped between 1930 and 1931 in accordance with the London Naval Treaty. Design and construction These ships were ordered in fiscal years 1900 (ACR-4 to ACR-6) and 1901 (ACR-7 to ACR-9) as part of the naval buildup touched off by the Spanish–American War. Together with the four immediately succeeding ships they were called the "Big Ten". They were originally intended to operate in the battle line with battleships. However, their role was changing even as they entered service. The 1904 report of the Navy's Bureau of Navigation, examining the results of the Russo-Japanese War, noted that "...the work of the armored cruisers was auxiliary to that of the battleships..." and "They can serve with battleships, but they can never take their place". In 1906 the US Navy's battleships were concentrated in the Atlantic, and three or four armored cruisers were assigned to the Asiatic Fleet in the Philippines to counter Japan's rising naval power. By 1912 the rapid development of dreadnought battleships and battlecruisers left the armored cruisers unable to successfully engage the newer capital ships. Armament These ships were originally armed with four /40 caliber Mark 5 guns in two twin turrets fore and aft. However, these were replaced with 8-inch/45 caliber Mark 6 guns by 1911 as a result of a gun bursting on Colorado in 1907. Fourteen /50 caliber Mark 6 guns were mounted in casemates on the sides. The large secondary armament, intended to combat torpedo boats, included eighteen /50 caliber rapid fire (RF) guns and twelve 3-pounder () RF guns. Two 1-pounder () saluting guns and two torpedo tubes were also carried. Armor In the development of these ships Captain Sigsbee, formerly of the ill-fated , successfully argued for adequate armor protection at the expense of speed. The belt armor was at the waterline with a upper belt, but was only at the ends. The turrets had up to on the faces. The protective deck had on the sloped sides and in the flat middle. The conning tower