The were a pair of armored cruisers built for the Imperial Japanese Navy (IJN) in the late 1890s. As Japan lacked the industrial capacity to build such warships itself, the ships were built in Britain. They were part of the "Six-Six Fleet" expansion program that began after the defeat of China during the First Sino-Japanese War of 1894–95. Between them, the sister ships participated in all four main naval battles of the Russo-Japanese War of 1904–05—the Battle of Port Arthur, the Battle off Ulsan, the Battle of the Yellow Sea, and the Battle of Tsushima—but played a much more minor role in World War I. Asama ran aground while searching for German commerce raiders in early 1915 and was under repair for the next two years. Tokiwa participated in the Battle of Tsingtao (1914) and also searched for commerce raiders. Both ships made training cruises during the war and continued to do so after 1918.
Asama continued to make training cruises until she ran aground again in 1935, after which she became a stationary training ship for the rest of her career. Tokiwa, converted into a minelayer in 1922–24, was placed in reserve in 1927 after an accidental explosion of several mines damaged her. The ship became a training minelayer in 1940. During the Pacific War of 1941-1945, Tokiwa participated in the occupation of the Gilbert Islands (1941) and Rabaul and Kavieng (1942) in New Guinea. Damaged by American aircraft shortly afterwards, the ship was forced to return to Japan for repairs. Tokiwa laid minefields during 1944–45 until she was twice damaged by mines in 1945. Shortly before the end of the war, American aircraft inflicted heavy damage on the ship and her crew had to beach her. Tokiwa was salvaged in 1947 and subsequently broken up for scrap. Asama survived the war intact and was scrapped in 1946–47.
Background and design The 1896 Naval Expansion Plan was made after the First Sino-Japanese War of 1894–95 and included four armored cruisers in addition to four more battleships, all of which had to be ordered from foreign shipyards as Japan lacked the capability to build them itself. Further consideration of the Russian building program caused the IJN to believe that the battleships ordered under the original plan would not be sufficient to counter the Imperial Russian Navy. Budgetary limitations prevented ordering more battleships and the IJN decided to expand the number of more affordable armored cruisers to be ordered from four to six ships. The revised plan is commonly known as the "Six-Six Fleet".Evans & Peattie, pp. 57–62 These ships were purchased using the £30,000,000 indemnity paid by China after losing the First Sino-Japanese War.Brook 1999, p. 125 Unlike most of their contemporaries which were designed for commerce raiding or to defend colonies and trade routes, these cruisers was intended as fleet scouts and to be employed in the battleline.Milanovich, p. 72
In June 1896, Sir Andrew Noble, then in Japan, telegraphed Armstrong Whitworth to lay down two stock cruisers. Work then began on a preliminary design based on an improved version of the earlier . Several iterations of the design were made before the IJN approved the final design on 21 August. This was over larger, more heavily armed, and slightly faster the Chilean armored cruiser.Brook 1999, pp. 107–09 The first ship of the class was laid down in October although the Japanese did not order the ships until 6 July 1897.Milanovich, p. 73
Description
The ships were long overall and between perpendiculars. They had a beam of and had an average draft of . The sisters displaced at normal load and at deep load. The ships had metacentric heights of .Milanovich, pp. 74, 80 Their crew consisted of 676 officers and enlisted men.Jentschura, Jung & Mickel, p. 72
The Asama-class ships had two 4-cylinder vertical triple-expansion steam engines, built by Humphrys, Tennant, each driving a single propeller shaft.Milanovich, p. 81 Steam for the engines was provided by a dozen cylindrical boilers and the engines were rated at a total of . The ships had a designed speed of and exceeded that speed during their sea trials, reaching from . They carried up to of coalBrook 1999, p. 109 and could steam for at a speed of .
Armament
The main armament for all of the "Six-Six Fleet" armored cruisers was four Armstrong Whitworth-built 45-caliber eight-inch guns in twin-gun turrets fore and aft of the superstructure. The electrically operated turrets were capable of 130° rotation left and right, and the guns could be elevated to +30° and depressed to −5°. The turret accommodated 65 shells, but could only be reloaded through doors in the turret floor and the ship's deck that allowed the electric winch in the turret to hoist shells up from the shell room deep in the hull.Milanovich, pp. 76–77 A total of 120 shells were carried for each gun. The guns were manually loaded and had a rate of fire about 1.2 rounds per minute. The 203-millimeter gun fired armor-piercing (AP) projectiles at a muzzle velocity of to a range of .Milanovich, p. 78
The secondary armament consisted of fourteen Elswick Ordnance Company "Pattern Z" quick-firing (QF), 40-caliber, guns. All but four of these guns were mounted in armored casemates on the main and upper decks, and their mounts on the upper deck were protected by gun shields. Their AP shells were fired at a muzzle velocity of .Friedman, p. 276; Milanovich, p. 78 Each gun was provided with total of 150 shells per gun. The ships were also equipped with a dozen 40-caliber QF 12-pounder 12-cwt guns"Cwt" is the abbreviation for hundredweight, 12 cwt referring to the weight of the gun. and eight QF 2.5-pounder Yamauchi guns as close-range defense against torpedo boats. The former gun fired , projectiles at a muzzle velocity of .Friedman, p. 114
The Asama-class ships were equipped with five submerged torpedo tubes, two on each broadside, and one above water in the bow. The Type 30 torpedo had a warhead and three range/speed settings: at , at or at .
Protection All of the "Six-Six Fleet" armored cruisers used the same armor scheme with some minor differences, with the Asama class using Harvey armor. The waterline belt ran the full length of the ships and its thickness varied from amidships to at the bow and stern. The thickest part of the belt covered the middle of the ship for a length of . It had a height of , of which was normally underwater. The upper strake of belt armor was thick and extended from the upper edge of the waterline belt to the main deck. It extended from the forward to the rear barbette. The Asama-class ships had a single transverse 5-inch armored bulkhead that closed off the forward end of the central armored citadel.Milanovich, pp. 80–81
The barbettes, gun turrets and the front of the casemates were all 6 inches thick while the sides and rear of the casemates were protected by of armor.Chesneau & Kolesnik, p. 225 The above-water torpedo tube in the bow was enclosed by a patch of 6-inch armor.Brook 1999, p. 107 The armor protecting the conning tower was in thickness. In addition to the Harvey armor, the Asama-class ships were unique among the "Six-Six Fleet" cruisers in that their armored deck was thick. The ships had 32 watertight compartments in their double bottom and an additional 131 between the bottom and the upper deck.Milanovich, p. 80
Ships + Construction dataShipBuilderLaid downLaunchedCompletedArmstrong Whitworth, Elswick20 October 189622 March 18988 February 18996 January 18976 July 189818 April 1899
Service
Before the start of the Russo-Japanese War in 1904, Tokiwa supported Japanese forces during the Boxer Rebellion in ChinaDix, p. 307 while Asama participated in the Coronation Review for King Edward VII in 1902.
Russo-Japanese War At the beginning of the Russo-Japanese War the sisters were assigned to the 2nd Division of the 2nd Fleet,Kowner, p. 465 although Asama was attached to the 4th Division of Rear Admiral Uryū Sotokichi for operations near Seoul, Korea. Just before the war began, the ship escorted Japanese troop convoys to Chemulpo, Seoul's port on the west coast, and helped to sink the two Russian warships stationed there on the first day of the war.Warner & Warner, pp. 188–95 Tokiwa participated in the Battle of Port Arthur that same day, when Vice Admiral Tōgō Heihachirō led the Combined Fleet in an attack on the Russian ships of the Pacific Squadron anchored just outside Port Arthur. Tōgō had expected the earlier surprise night attack by his destroyers to be much more successful than it was, anticipating that the Russians would be badly disorganized and weakened, but they had recovered from their surprise and were ready for his attack.Forczyk, pp. 42–43
In early March Tokiwa was reassigned to the 3rd Division and Asama joined her shortly afterwards.Corbett, I, pp. 127, 142 They participated in the action of 13 April when Tōgō successfully lured out two battleships of the Russian Pacific Squadron. During this action, the sisters engaged the Russian cruisers that preceded the battleships before falling back on Tōgō's battleships.Warner & Warner, pp. 236–38 When the Russians spotted the five battleships of the 1st Division, they turned back for Port Arthur and the battleship struck a minefield laid by the Japanese the previous night. The ship sank in less than two minutes after one of her magazines exploded.Forczyk, pp. 45–46
Tokiwa rejoined the 2nd Division a few days later and the division was tasked to contain the Russian armored cruisers based at Vladivostok. It failed to do so until 13 AugustCorbett, I, pp. 188–89, 191–96, 283–89, 319–25, 337–51 when the latter tried to rendezvous with the ships that attempted to breakout from Port Arthur. Unbeknownst to the Russians, Tōgō had defeated the ships from Port Arthur during the Battle of the Yellow Sea on 10 August and the Russian squadron from Vladivostok was intercepted off Ulsan, Korea by the 2nd Division. The steering of the Russian cruiser was damaged early in the battle and the Russians made several attempts to prevent the Japanese from concentrating fire on her, but were ultimately forced to abandon her to her fate. Kamimura left Rurik to the tender ministrations of his reinforcements and pursued the two remaining Russian ships for a time before breaking off pursuit prematurely based on an incorrect report that his flagship had expended most of her ammunition. Tokiwa only suffered three men wounded during the battle.Brook 2000, pp. 43, 45
In the meantime, Asama remained on blockade duty off Port Arthur and participated in a minor way in the Battle of the Yellow Sea. She was coaling when the Pacific Squadron sortied and took some time to intercept the Russian ships. The battle was almost over by then and the ship only engaged them for the last hour or so of the battle.Corbett, I, pp. 389, 397–98, 417 After the battle, the sisters were refitted and assigned to different units, escorting troop convoys to northern Korea and blockading the Tsugaru Strait until the Russian ships from the Baltic Fleet approached Japan in mid-1905.Corbett 1994, II, pp. 47, 52, 97, 104, 153, 159–60, 176–77, 217
Battle of Tsushima