Never Built Japanese Battleships: Super B-65 B-64

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Never Built IJN Battleships B-65


From the B-65-class at least two vessels were planned originally. The origin of this class was in 1920s reasons. Due to the restrictions imposed by the Washington Naval Treaty of 1922 and the London Naval Treaty of 1930, the IJN was in a serious disadvantage in case of global war with the Royal Navy and the US Navy. The IJN staff concluded that, in a similar way that with the Russo-Japanese War, a decisive battle with limited forces involved would be the only way to obtain a decisive victory against any Major Power. In 1936, the IJN formed the Night Battle Force (Yasen Butai). The concept behind this night battle force was that this force had the aim to attack the hypothetical enemy’s, usually envisioned by the Japanese to be the US Pacific Fleet, outer defense ring of cruisers and destroyers at night. Once the outer defense ring was broken, IJN cruisers and destroyers were to launch torpedo attacks on the enemy’s battleships. What remained of the enemy fleet was then to be finished-off by the IJN’s main battleship line the following day.

To perform this ambitious strategy fast battlecruisers were necessary. The IJN assigned one division of fast battleships or battlecruisers to give additional firepower to the nocturnal attacks. The Kongō-class battlecruiser were initially assigned to this role and were upgraded to fast battleships over a seven-year period from 1933-1940. The IJN planned to eventually replace the four Kongō battleships with four heavy, “super” cruisers. As envisioned by the IJN in 1936, these ships, the B-65 cruisers, would mount 12-inch guns, carry armor designed to withstand hits from 8-inch shells, and be capable of speeds up to 40 knots. They would be designated as “super-A-class cruisers” to signify their greater status than the A-class ships (heavy cruisers).

The implementation to develop the cruiser class was finalized as part of the IJN’s Circle Five and Circle Six warship construction plans of 7 January 1941. The plan called for six B-65s to be built in two increments, with the first two to be constructed in Circle 5 with the remainder in Circle 6. By this time, Japanese intelligence had learned the specifications for the United States Navy’s Alaska-class large cruisers,which had been authorized for creation by the passage of the Two-Ocean Navy Act and ordered on 5 September 1940.The Japanese believed that these ships would form part of the American battle fleet’s screen in times of war. Thus, the B-65s were now intended to counter the threat posed by the Alaska-class cruisers.

However, after the Pacific War started, the IJN experienced a more necessity of aircraft carriers and soon it was broadly extended that the war and the concept of the decisive battle based on strong battleships and cruisers was quickly obsolete. Even though the B-65 project and ship construction was still on going and schedule to finished in 1945 and 1946, in practice it was never finalized and the builders will never get official contracts.


Type: Super Type A cruiser
Standard: 31,905 t (31,401 long tons)
Full-load: 35,000 t (34,000 long tons)
240 m (790 ft) length at the waterline
246.2 m (808 ft) length overall
Beam: 27.2 m (89 ft)[1]
Draft: 8.8 m (29 ft) (trial)
Propulsion: Four sets of geared turbines and eight Kampon boilers would yield 170,000 metric horsepower (167,674 shaft horsepower); this would have been able to drive the ship at 33 kn (38 mph; 61 km/h)
Endurance: 8,000 mi (13,000 km) at 18 kn (21 mph; 33 km/h)
9 × 310 mm (12.2 in)/50 caliber guns (3 × 3)[1]
16 × 100 mm (3.9 in)/65 caliber dual-purpose guns (8 × 2)
12 × 25 mm (1 in) Type 96 anti-aircraft guns (6 × 2)
4 × 13 mm (0.5 in) Hotchkiss machine guns (2 × 2)
8 × 610 mm (24 in) torpedo tubes (4 × 2) firing Type 93 torpedos
210 mm (8.3 in) to 190 mm (7.5 in) barbettes 190 mm (7.5 in) side armor inclined 20 degrees
125 mm (5 in) armored deck 180 mm (7.1 in) conning tower sides 125 mm (4.9 in) conning tower roof

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