Amagi-class battlecruiser

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Line drawing of this type of vessel; the ship had a long hull, two tall masts, five gun turrets, and two large funnels.
Design for the Amagi class
Class overview
Builders
OperatorsImperial Japanese Navy
Preceded byKongō class
Succeeded byDesign B-65
Built1920–1922
Planned4
Completed1 (converted into an aircraft carrier)
Cancelled3
Lost1
Scrapped3
General characteristics
TypeBattlecruiser
Displacement
  • 41,217 t (40,566 long tons) (normal)
  • 47,000 t (46,260 long tons) (
    full load
    )
Length251.8 m (826 ft)
Beam30.8 m (101 ft)
Draft9.5 m (31 ft)
Installed power
Propulsion4 shafts; 4 steam turbines
Speed30 knots (56 km/h; 35 mph)
Range8,000 nmi (15,000 km; 9,200 mi) at 14 knots (26 km/h; 16 mph)
Complement1,600
Armament
Armor
  • Belt: 250 mm (9.8 in)
  • Deck: 95 mm (3.7 in)
  • Conning Tower: 75–360 mm (3.0–14.2 in)
  • Torpedo bulkheads: 73 mm (2.9 in)
  • Barbettes: 230–280 mm (9.1–11.0 in)

The Amagi class (天城型, Amagi-gata) was a

Eight-eight fleet in the early 1920s. The ships were to be named Amagi, Akagi, Atago, and Takao. The Amagi design was essentially a lengthened version of the Tosa-class battleship, but with a thinner armored belt and deck, a more powerful propulsion system, and a modified secondary armament arrangement. They were to have carried the same main battery of ten 41 cm (16.1 in) guns and been capable of a top speed of 30 knots
(56 km/h; 35 mph).

Limitations imposed by the 1922

Kido Butai during the Second World War, participating in the Japanese attack on Pearl Harbor before being sunk at the Battle of Midway
.

Design

Dimensions and machinery

The ships had a planned displacement of 41,217 tonnes (40,566

waterline, and 251.8 m (826 ft) overall. The ships would have had a beam of 30.8 m (101 ft) and a draft of 9.5 m (31 ft)[1] and would have used four propeller shafts, powered by Gihon steam turbines. The design staff intended to use turbines, which were to be powered by 19 Kampon water-tube boilers, eleven of which were oil-fired, while the other eight were to have mixed oil and coal for fuel. This system was designed to provide 131,200 shaft horsepower (97,800 kW) for a top speed of 30 knots (56 km/h; 35 mph). The planned fuel stores amounted to 3,900 tons of oil and 2,500 tons of coal. The ships had a planned cruising speed of 14 knots (26 km/h; 16 mph), and with full fuel stores, the ships would have had a maximum range of 8,000 nautical miles (15,000 km; 9,200 mi).[1]

Armament

The ships were to be equipped with a main battery of ten

armor-piercing projectiles with a 224 kg (494 lb) propellant charge at 790 m/s (2,600 ft/s), at a rate of fire between 1.5 and 2.5 rounds per minute. Each gun had 90 rounds and an approximate barrel life of 250–300 shots. The turrets would have been arranged along the centerline: two superfiring turrets fore, and three in line aft of the superstructure. The gun turrets weighed 1,004 tons (1,020 mt), and allowed for depression of −5 degrees and elevation of 30 degrees.[2]

The secondary battery was to have consisted of sixteen

12 cm (4.7 in) L/45 anti-aircraft guns were to have been mounted amidships, along with eight 61 cm (24 in) above-water torpedo tubes.[1]

Armor

It was planned that the Amagi class would be protected by a main belt 254 mm (10.0 in) thick, sloped at 12 degrees, and a torpedo bulkhead 73 mm (2.9 in) thick. The main battery barbettes were designed to have between 230–280 mm (9.1–11.0 in) of armor plating, and the conning tower would have had armor ranging in thickness from 76 mm (3 in) to a maximum of 356 mm (14.0 in). Deck armor was to have been 98 mm (3.9 in) thick.[1]

Background

Experiences in the

"Eight-eight" policy. This plan originally called for a fleet of eight battleships and eight armored cruisers that would all be under ten years old (later changed to eight battlecruisers and reduced to eight years old). However, the advent of the dreadnought battleship crippled this plan at the beginning; given Japan's weak and underdeveloped economy and the enormous strain that had been put on it during the Russo-Japanese War (Japan emerged from the war victorious, but bankrupt),[4] the launch of HMS Dreadnought was a "disaster" for Japan.[5]

In 1907, Japan was halfway to the eight-eight, with two newly delivered battleships (the

pre-dreadnought), and armored cruisers were seemingly useless in the face of the new battlecruisers being laid down by Great Britain and Germany. The IJN recognized this, and proposed in 1909 that two battlecruisers be ordered from British plans, with one to be built in Great Britain and one to be built at home. These two ships became the Kongō class. Another pair of Kongos were later built in Japan.[5]

In 1910, there was still authorization for one battleship and four armored cruisers. This battleship, a more heavily armored version of the Kongō-class battlecruisers, became Japan's first

super-dreadnought, Fusō. With these ships, Japan appeared to be getting closer to the eight-eight goal; however, these new ships represented a "new level of naval strength" for the IJN, and they made all previous Japanese capital ships obsolete. This meant that any naval planner aiming for an eight-eight fleet would have to call for seven more battleships and four more battlecruisers[5] at a time when Japan was trying to weather a worldwide economic depression.[4]

After proposals from the IJN in 1911 and 1912 for massive shipbuilding programs, the Cabinet compromised down to a "four-four" plan; under this, three new battleships (the other

Diet of Japan in 1915; it aimed to have the eight battleships and four battlecruisers by 1923 with the building of two Nagato-class and two Tosa-class battleships. The problem with this was that the old plan intended all of the ships of the eight-eight fleet to be under eight years old; by the time these new ships were completed, Fusō and the first two Kongō ships would be past their replacement age.[7]

The plan was approved in 1917, along with funding for two battlecruisers which became the Amagi class. In late 1917, the Navy proposed to expand the eight-four plan by adding two more battlecruisers; this was approved, and two more Amagi-class ships were ordered. However, having eight 41 cm (16 in) gun ships (four battleships and four battlecruisers) on order put an enormous financial strain on Japan, which was spending about a third of its national budget on the Navy. The massive size and scale of its building program was rapidly driving up the cost of naval construction and armament.[7]

Construction, cancellation, and conversion

A large ship, covered with scaffolding, sits in harbor under a large gantry.
Akagi after her launch in April 1925; she had already been converted to an aircraft carrier

Yokosuka naval yard. The projected completion dates for the first pair of ships were December and November 1923, respectively. Atago was laid down in Kobe at the Kawasaki shipyard on 22 November 1921, and was projected to be finished in December 1924. Takao, the fourth and final ship of the class, was laid down at the Mitsubishi shipyard in Nagasaki on 19 December 1921, and was also projected to be completed in December 1924.[1] The ships were named after several mountains: Amagi, Akagi, Atago, and Takao.[A 3] Takao was initially to have been named Ashitaka after Mount Ashitaka.[8]

The

Strait of Tsushima. The rest of their guns were placed in reserve and scrapped in 1943.[12]

The incomplete Amagi soon after the earthquake.

The September 1923 Great Kantō earthquake in Tokyo caused significant stress damage to the hull of Amagi. The structure was too heavily damaged to be usable, and conversion work was abandoned. Amagi was stricken from the navy list and sold for scrapping, which began on 14 April 1924. The other two ships, Atago and Takao, were officially canceled two years later (31 July 1924) and were broken up for scrap in their slipways.[1] The incomplete Tosa-class battleship Kaga, on which work had stopped on 5 February 1922, was reordered as a carrier to replace Amagi.[13]

Akagi's career as an aircraft carrier

An aircraft carrier steaming at full speed. Thick black smoke billows from its curved smoke stack.
Akagi on trials in 1927; the ship originally had two short take-off decks and a main landing deck
Main article: Japanese aircraft carrier Akagi

The conversion of Akagi began on 19 November 1923, and was completed in March 1927. However, the strange assortment of flight decks fitted on Akagi—a main landing deck superimposed over two short take-off decks—proved unsatisfactory, and the ship was withdrawn from active service in 1935 for modernization. The lower two flight decks were removed, the main deck was lengthened to 250 m (820 ft), and a third elevator was added.[14] Refitting was completed in 1938.[15] Akagi supported operations off China in early 1939 and 1940, and underwent an overhaul in November 1940.[15]

Akagi served as Vice Admiral

Kido Butai—composed of the carriers Akagi, Kaga, Hiryū, Sōryū, Shōkaku, and Zuikaku, supported by escorts—launched two waves of airstrikes on the American base at Pearl Harbor in a devastating surprise attack. American losses included four battleships and two destroyers sunk and nearly 200 aircraft destroyed.[17][18][19]

On 19 February 1942, aircraft from Akagi, Hiryū, Sōryū, and Kaga participated in the bombing of Darwin, Australia.[19][20] On 27 February, their bombers severely damaged the old American carrier USS Langley, which was subsequently scuttled by her escort.[21]

Akagi and the carriers Hiryū and Sōryū were sent in March 1942 with a mixed force of battleships, cruisers, and destroyers to the Indian Ocean to engage the British fleet there and to support planned attacks on

Ceylon. In the Easter Sunday Raid on 5 April, aircraft from the carriers struck the British base at Colombo, destroying a number of aircraft and sinking an armed merchant cruiser and the old destroyer HMS Tenedos in the harbor.[19][22] The Japanese fleet also spotted the heavy cruisers HMS Dorsetshire and HMS Cornwall at sea; both ships were sunk in an overwhelming air attack.[19] On 9 April the carriers attacked British installations at Trincomalee, destroying aircraft and sinking the carrier HMS Hermes, the destroyer HMAS Vampire, and the corvette HMS Hollyhock.[23]

Battle of Midway

Main article: Battle of Midway

In late May 1942, in an effort to draw out and destroy the elusive American carriers, Japanese forces organized attacks on the

Aleutian Islands in Alaska and Midway Atoll in the Western Pacific.[24] Nagumo, aboard Akagi, led Kaga, Sōryū, and Hiryū and the support ships of the First Carrier Striking Force to Midway.[25][26] In the initial attack, Japanese planes neutralized a small force of fighter aircraft and inflicted heavy damage to American installations.[24][27] Torpedo planes and dive-bombers sent from Midway to harry the Japanese fleet had little effect, but the Japanese attack plan had been deciphered by codebreakers, and the American carriers' planes were already en route.[28] Torpedo bombers from USS Hornet, USS Enterprise, and USS Yorktown joined the attack in succession, forcing the Japanese carriers to maneuver violently to avoid torpedoes and rendering them unable to launch additional aircraft.[29] American dive-bombers, arriving late after difficulty locating the fleet, soon landed fatal strikes on Akagi, Kaga, and Sōryū.[29] Yorktown, handicapped by hits from Hiryū's bombers, managed to return to the fight only to take two torpedo hits a couple of hours later.[29] The burning Yorktown was abandoned, but her scouts pinpointed Hiryū's location, and bombers from Enterprise put Hiryū out of action with four bomb strikes.[29] Japan lost all four carriers of the First Carrier Striking Force at Midway.[30]

Notes

  1. calibers
    , meaning that the gun is 45 times long as it is in diameter.
  2. ^ While the Satsuma-class battleships were technically "semi-dreadnoughts" due to their heavy secondary battery, they were still made obsolete by Dreadnought.
  3. ^ Conway's All the World's Fighting Ships (p. 235) states that Takao was named for the town of Takao, Formosa, and some sources repeat this. However, the name Takao for Japanese warships predated the renaming of the town, and Lacroix (p. 122) states that the name was simply re-used for the battlecruiser.

References

  1. ^ a b c d e f g h Gardiner and Gray (1984), p. 235
  2. ^ DiGiulian, Tony (19 April 2007). "Japanese 41 cm/45 (16.1") 3rd Year Type, 40 cm/45 (16.1") 3rd Year Type". Navweaps.com. Archived from the original on 24 January 2009. Retrieved 18 January 2009.
  3. ^ DiGiulian, Tony (23 August 2007). "Japanese 5.5"/50 (14 cm) 3rd Year Type". Navweaps.com. Archived from the original on 6 January 2009. Retrieved 18 January 2009.
  4. ^ a b Gardiner and Gray (1984), p. 222
  5. ^ a b c Gardiner and Gray (1984), p. 223
  6. ^ Gardiner and Gray (1984), pp. 222–223
  7. ^ a b Gardiner and Gray (1984), p. 224
  8. ^ Katagiri, p. 93
  9. ^ See: Washington Naval Treaty, Chapter II, Part III, Section II
  10. ^ Friedman (1983), p. 43
  11. ^ See: Washington Naval Treaty, Chapter I, Article IX
  12. ^ Gibbs & Tamura (1982), pp. 192, 194
  13. ^ Gardiner and Gray eds. (1984), p. 232
  14. ^ Stille, p. 12
  15. ^ a b Kotani, Ken. "Pearl Harbor: Japanese planning and command structure" in Marston (2005), pp. 32–33
  16. ^ "Akagi (Aircraft Carrier, 1927–1942)". Naval History & Heritage Command. 21 March 1999. Archived from the original on 10 May 2010. Retrieved 6 October 2009.
  17. ^ Hoyt (2001), pp. 225–228
  18. ^ Kotani, Ken. "Pearl Harbor: Japanese planning and command structure" in Marston (2005), pp. 40–41
  19. ^ a b c d Ireland (1998), p. 190
  20. ^ Hoyt (2001), p. 260
  21. ^ "Langley". Dictionary of American Naval Fighting Ships. Navy Department, Naval History and Heritage Command. Retrieved 6 October 2009.
  22. ^ Hoyt (2001), p. 268
  23. ^ Ireland (1998), p. 191
  24. ^ a b Ireland (1998), p. 197
  25. ^ Love, Robert. "The Height of Folly" in Marston (2005), p. 89
  26. ^ Hoyt (2001), p. 293
  27. ^ Hoyt (2001), p. 295
  28. ^ Love, Robert. "The Height of Folly" in Marston (2005), p. 93
  29. ^ a b c d Ireland (1998), p. 200
  30. ^ Love, Robert. "The Height of Folly" in Marston (2005), p. 97

Bibliography

External links

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