Fusō-class battleship
The Fusō-class battleships were a pair of dreadnought battleships built for the Imperial Japanese Navy before World War I and completed during the war. Both patrolled briefly off the coast of China before being placed in reserve at the war's end. In 1922, became the first battleship in the IJN to successfully launch aircraft.
During the 1930s, both ships underwent a series of modernizations and reconstructions. was modernized in two phases, while Yamashiro was reconstructed from 1930 to 1935. The modernization increased their armor, replaced and upgraded their machinery, and rebuilt their superstructures into a distinctive pagoda mast style. Despite the expensive reconstructions, both vessels were obsolescent by World War II, and neither saw significant action in the early years of the war. Fusō served as a troop transport in 1943, while Yamashiro was relegated to training duty in the Inland Sea. Both received better anti-aircraft weapons in 1944 before transferring to Singapore in August 1944.
Fusō and Yamashiro were the only two Japanese battleships at the Battle of Surigao Strait, the southernmost action of the Battle of Leyte Gulf, and both were lost in the early hours of 25 October 1944. Fusō burned and sank within an hour of being torpedoed. Yamashiro encountered six U.S. Navy battleships and eight cruisers, sinking along with Vice Admiral Shōji Nishimura. Only ten crew members from each ship survived.
Background
The design of the Fusō-class battleships was shaped both by the ongoing international naval arms race and a desire among Japanese naval planners to maintain a fleet of capital ships powerful enough to defeat the United States Navy in an encounter in Japanese territorial waters. The IJN's fleet of battleships had proven highly successful in 1905, the last year of the Russo-Japanese War, which culminated in the destruction of the Russian Second and Third Pacific Squadrons at the Battle of Tsushima.In the aftermath of that war, the Japanese Empire immediately turned its focus to the two remaining rivals for imperial dominance in the Pacific Ocean: Britain and the United States. Satō Tetsutarō, a Japanese Navy admiral and military theorist, speculated that conflict would inevitably arise between Japan and at least one of its two main rivals. To that end, he called for the Japanese Navy to maintain a fleet with at least 70% as many capital ships as the US Navy. This ratio, Satō theorized, would enable the Imperial Japanese Navy to defeat the US Navy in one major battle in Japanese waters in any eventual conflict. Accordingly, the 1907 Imperial Defense Policy called for the construction of a battle fleet of eight modern battleships, each, and eight modern armored cruisers, each. This was the genesis of the Eight-Eight Fleet Program, the development of a cohesive battle line of sixteen capital ships.
The launch of in 1906 by the Royal Navy raised the stakes, and complicated Japan's plans. Displacing and armed with ten guns, Dreadnought rendered all existing battleships obsolete by comparison. The launch of the battlecruiser the following year was a further setback for Japan's quest for parity. When the two new s and two armored cruisers, launched by 1911, were outclassed by their British counterparts, the Eight-Eight Fleet Program was restarted.
The first battleships built for the renewed Eight-Eight Fleet Program were the two dreadnoughts of the, ordered in 1907 and laid down in 1908. In 1910, the Navy put forward a request to the Diet to secure funding for the entirety of the program at once. Because of economic constraints, the proposal was cut first by the Navy Ministry to seven battleships and three battlecruisers, then by the cabinet to four armored cruisers and a single battleship. The Diet amended this by authorizing the construction of four battlecruisers and one battleship, later named Fusō, in what became the Naval Emergency Expansion bill.
Design
Fusō was designed to work in conjunction with the four battlecruisers. After coordination with the British on the Kongō class, Japanese designers had access to the latest British design studies in naval architecture and were now able to design their own capital ships. In an effort to outmatch the American, planners called for a ship armed with twelve guns and faster than the of their rivals. Vickers files show that the Japanese had access to the designs for double- and triple-gun turrets, yet opted for six double turrets over four triple turrets.The final design—designated A-64 by the IJN—called for a displacement of with twelve guns in six double turrets with a top speed of. This design was superior to its American counterparts in armament, armor and speed, thus following the doctrine the Japanese had used since the First Sino-Japanese War of 1894–95 of compensating for quantitative inferiority with qualitative superiority.
Description
The ships had a length of overall. They had a beam of and a draft of. They displaced at standard load. Their crew consisted of 1,198 officers and enlisted men in 1915 and 1,396 in 1935. During World War II, the crew probably totalled around 1,800–1,900 men.During the ships' modernization during the 1930s, their forward superstructures were enlarged with multiple platforms added to their tripod foremasts. The rear superstructures were rebuilt to accommodate mounts for anti-aircraft guns and additional fire-control directors. Both ships were also given torpedo bulges to improve their underwater protection and to compensate for the weight of the additional armor. In addition, their sterns were lengthened by. These changes increased their overall length to, their beam to and their draft to. Their displacement increased nearly to at deep load.
Propulsion
The Fusō-class ships had two sets of Brown-Curtis direct-drive steam turbines, each of which drove two propeller shafts. The medium-pressure turbines drove the wing shafts while the high- and low-pressure turbines drove the inner shafts. The turbines were designed to produce a total of, using steam provided by 24 Miyahara-type water-tube boilers, each of which consumed a mixture of coal and oil. The ships had a stowage capacity of of coal and of fuel oil, giving them a range of at a speed of. Both ships exceeded their designed speed of during their sea trials; Fusō reached from and Yamashiro exceeded that with from.During their 1930s modernization, the Miyahara boilers on each ship were replaced by six new Kanpon oil-fired boilers, fitted into the former aft boiler room, and the forward funnel was removed. The Brown-Curtis turbines were replaced by four geared Kanpon turbines with a designed output of. On her trials, Fusō reached a top speed of from. The fuel storage of the ships was increased to a total of of fuel oil that gave them a range of at a speed of.
Armament
The twelve 45-calibre 14-inch guns of the Fusō class were mounted in six twin-gun turrets, numbered from front to rear, each of which weighed. The turrets had an elevation capability of −5/+20 degrees. They were arranged in an uncommon 2-1-1-2 style with superfiring pairs of turrets fore and aft; the middle turrets were not superfiring, and had a funnel between them. The decision to use six twin turrets rather than four triple turrets greatly affected the entire design of the class because the two extra turrets required a longer ship and increased the amount of armor required to protect the ship. The location of the third and fourth turrets proved particularly problematic to the design of the class because the amidships turrets were not superfiring as in the subsequent s. This further increased the length of the ships because the barrels of the upper turret did not protrude over the lower turret, requiring more space than a pair of superfiring turrets. Mounted amidships along the centerline of the ship, they had restricted arcs of fire, and their position forced the boiler rooms to be placed in less than ideal locations. Another complication was the need to fit extra insulation and air conditioning in the magazines of the amidships turrets to protect them from the heat generated in the adjacent boiler rooms. Originally both amidship gun turrets faced to the rear, but Fusōs turret No. 3 was moved to face forward during her reconstruction in order to accommodate additional platforms around her funnel.The main battery of the Fusō class underwent multiple modernizations throughout the ships' careers. During the first reconstruction of both vessels, the elevation of the main guns was increased to −5/+43 degrees, giving a maximum firing range of. The recoil mechanism of the guns was also changed from a hydraulic to pneumatic system, which allowed for a faster firing cycle of the main guns.
By World War II, the guns used Type 91 armor-piercing, capped shells. Each of these shells weighed and had a muzzle velocity of. They had a maximum range of at +30 degrees of elevation and at +43 degrees after modernization. Also available was a high-explosive shell that had a muzzle velocity of. A special Type 3 San Shiki incendiary shrapnel shell was developed in the 1930s for anti-aircraft use.
As built, the Fusō class was fitted with a secondary armament of sixteen 50-caliber six-inch guns mounted in single casemates along the sides of the hull at the level of the upper deck. Eight guns were mounted per side, and each had an arc of fire of 130 degrees and a maximum elevation of +15 degrees. Each gun could fire a high-explosive projectile a maximum distance of at a rate of between four and six shots per minute. During their reconstruction in the 1930s, the maximum elevation of the guns was increased to +30 degrees, which increased their maximum range by approximately.
The ships also mounted five or six 40-caliber 8 cm/40 3rd Year Type naval gun| anti-aircraft guns. The high-angle guns were in single mounts on both sides of the forward superstructure, both sides of the second funnel, and each side of the aft superstructure. Each of these guns had a maximum elevation of +75 degrees, and could fire a projectile with a muzzle velocity of to a maximum height of. Both ships were equipped with six submerged torpedo tubes, three on each broadside.
The Fusō class's secondary armament changed significantly over time. During the modernizations of the 1930s, all of the 76 mm guns were replaced with eight 40-caliber dual-purpose guns. These guns were fitted on both sides of the fore and aft superstructures in four twin-gun mounts. When firing at surface targets, the guns had a range of ; they had a maximum ceiling of at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was around 8 rounds per minute. During reconstruction, the two foremost 152 mm guns were also removed.
The light AA armament of the Fusō class changed dramatically from 1933 to 1944. During the first reconstruction, Fusō was fitted with four quadruple machine-guns, while Yamashiro was fitted with eight twin gun mounts. Both weapons were license-built French Hotchkiss designs. The 25 mm guns were mounted on the Fusō class in single, double and triple mounts. This model was the standard Japanese light anti-aircraft gun during World War II, but it suffered from severe design shortcomings that rendered it a largely ineffective weapon. The twin and triple mounts "lacked sufficient speed in train or elevation; the gun sights were unable to handle fast targets; the gun exhibited excessive vibration; the magazine was too small, and, finally, the gun produced excessive muzzle blast". The configuration of the anti-aircraft guns varied significantly; by the end of their final reconstruction, the Fusō class mounted eight twin mounts. In 1943, seventeen single and two twin-mounts were added for a total of 37. In August 1944, both were fitted with another twenty-three single, six twin and eight triple-mounts, for a total of 96 anti-aircraft guns in their final configuration.