The threat of the Kongō-class on American lines of communication and logistics leading up to World War II highly influenced the U.S. Navy's decision to order the Iowa-class fast battleships.

[5] The final design of the battlecruisers resulted in an improved version of the Lion class, displacing an estimated 27,940 tonnes (27,500 long tons).

They were designed to produce a total of 65,000 shaft horsepower (48,000 kW), using steam provided by 36 Yarrow or Kampon water-tube boilers, with working pressures ranging from 17.1 to 19.2 atm (1,733 to 1,945 kPa; 251 to 282 psi).

This increased their range to 8,930 nautical miles (16,540 km; 10,280 mi) at 14 knots and allowed the fore funnel to be removed, which greatly decreased smoke interference with the bridge and fire-control systems.

Coupled with the addition of external torpedo bulges, this reduced their speed to 26 knots (48 km/h; 30 mph) and caused the IJN to reclassify them as battleships.

[17] As built, the Kongō class was fitted with a secondary armament of sixteen 15 cm/50 guns mounted in single casemates along the sides of the hull at the level of the upper deck.

This model was the standard Japanese light anti-aircraft gun during World War II, but severe design shortcomings rendered it largely ineffective.

The Kongō-class battlecruisers were designed with the intention of maximizing speed and maneuverability, and as such were not as heavily armoured as later Japanese capital ships.

[7] Even after these modifications, the armour capacity of the Kongō class remained much less than that of newer capital ships, a factor which played a major role in the sinking of Hiei and Kirishima at the hands of U.S. Navy cruisers and battleships in 1942.

[3] On 23 August 1914, Japan formally declared war on the German Empire as part of her contribution to the Anglo-Japanese Alliance, and Kongō was deployed near Midway Island to patrol the communications lines of the Pacific Ocean, attached to the Third Battleship Division of the First Fleet.

[29] On 1 November 1924, Kongō docked at Yokosuka for modifications which improved fire control and main-gun elevation, and increased her antiaircraft armament.

[3][30][N 2] Japan's withdrawal from the London Naval Treaty[32] led to reconstruction of her forward tower to fit the pagoda mast style of design, improvements to the boilers and turbines, and reconfiguration of the aircraft catapults aft of Turret 3.

[3] Kongō provided cover for Japanese carriers during attacks on the Dutch East Indies in February and Ceylon in March and April.

[3][30] Kongō and Hiei were part of the Second Fleet Main Body during the Battle of Midway, but were diverted north on 9 June to assist in the invasion of the Aleutian Islands.

[34][35] Following armament and armour upgrades in late 1943 and early 1944,[3] Kongō sailed as part of Admiral Jisaburō Ozawa's Mobile Fleet during the Battle of the Philippine Sea.

[3][39] Kongō and an escort, Urakaze, were sunk northwest of Taiwan on 21 November 1944 by the submarine USS Sealion, after being hit on the port bow by two or three torpedoes.

[42] After undergoing minor reconstructions in 1924 and 1927, Hiei was demilitarized in 1929 to avoid being scrapped under the terms of the Washington Treaty; she was converted to a training ship in Kure from 1929 to 1932.

[31][42] Hiei provided escort cover during carrier raids on Darwin in February 1942, before a joint engagement with Kirishima that sank an American destroyer in March.

[42][45] Following carrier escort duty during the Battles of the Eastern Solomons and Santa-Cruz, Hiei departed as the flagship of Rear Admiral Hiroaki Abe's Combat Division 11 to bombard Henderson Field on the night of 12–13 November 1942.

[46][47] When the fleet encountered Rear Admiral Daniel Callaghan's Task Group in Ironbottom Sound, the First Naval Battle of Guadalcanal ensued.

[49][42][47] In particular, San Francisco scored a pair of 8-inch (203 mm) hits that penetrated Hiei's belt and left her suffering a severe rudder jam, unable to maneuver.

After serving as a transport and support-ship during the Second Sino-Japanese War, Kirishima escorted the aircraft carrier strikeforce bound for the attack on Pearl Harbor in December 1941.

Following the start of World War II, Kirishima served as an escort during carrier attacks on Port Darwin and the Dutch East Indies.

[52] She once again served escort duty during the disastrous Battle of Midway, before transferring to Truk Lagoon in preparation for operations against American landings on Guadalcanal.

[15] After a short patrolling duty off Sasebo, Haruna suffered a breech explosion during gunnery drills on 12 September 1920; seven crewmen were killed and the No.

The process upgraded her propulsion capabilities, enabled her to carry and launch floatplanes, increasing her armour capacity by over 4,000 tons,[7] and was shortly thereafter reclassified as a Battleship.

[15] On the eve of the commencement of World War II, Haruna sailed as part of Vice-Admiral Nobutake Kondō's Southern Force.

[53] She participated in the major Japanese offensives in the southern and southwestern Pacific in early 1942, before sailing as part of the carrier-strike force during the Battle of Midway.

[15] Haruna bombarded American positions at Henderson Field at Guadalcanal, and provided escort to carriers during the Solomon Islands campaign.

In 1943, she deployed as part of a larger force on multiple occasions to counter the threat of American carrier strikes, but did not actively participate in a single battle.