Amagi-class battlecruiser

Amagi-class battlecruiser. The Amagi class was a planned class of four fast capital ships for the Imperial Japanese Navy designed in the early 1920s. Intended as battlecruiser counterparts to the concurrent Tosa-class battleship, they were part of Japan's ambitious "Eight-eight fleet" naval expansion program. Their construction was halted and ultimately cancelled under the terms of the Washington Naval Treaty, with only one hull, Akagi, being converted into an aircraft carrier.

Design and description

The design of the Amagi class was a direct response to foreign developments, particularly the British HMS Hood and the American Lexington-class battlecruiser. Naval architects under the Imperial Japanese Navy General Staff sought a vessel that combined the firepower of a battleship with the speed of a cruiser, prioritizing a main battery of ten 41 cm/45 3rd Year Type naval gun in five twin turrets. Propulsion was provided by four Gihon geared steam turbines fed by 19 Kampon oil-fired boilers, designed to produce 131,200 shaft horsepower for a top speed of 30 knots. Armor protection, while substantial with a 250 mm main belt and a 356 mm conning tower, was deliberately lighter than that of the Tosa class to achieve this high speed, adhering to the classic battlecruiser philosophy of sacrificing protection for velocity. The secondary armament was to consist of 16 single 14 cm/50 3rd Year Type naval gun and an anti-aircraft suite of four 12 cm/45 10th Year Type naval gun, reflecting the growing threat from aerial attack noted after World War I.

Construction and cancellation

Construction on the four ships began at major Japanese naval arsenals following the approval of the Eight-eight fleet plan by the Diet of Japan. Amagi and Akagi were laid down at Yokosuka Naval Arsenal and Kure Naval Arsenal respectively in late 1920, while Atago and Takao followed at Kawasaki Shipbuilding Corporation in Kobe and Mitsubishi Shipyard in Nagasaki in 1921. Work progressed until the signing of the Washington Naval Treaty in February 1922, which imposed strict limits on capital ship tonnage for signatories including Japan, the United Kingdom, and the United States. The treaty mandated the cancellation of all capital ships under construction, dooming the Amagi class. A clause allowing the conversion of two capital ship hulls into aircraft carriers saved Akagi and Amagi from the scrapyard initially, but the 1923 Great Kantō earthquake critically damaged the Amagi hull at Yokosuka, leading to its scrapping. Akagi alone was completed as a carrier, which later fought at the Battle of Midway.

Planned ships

Four ships of the class were planned, all named after mountains significant in Japanese culture and history. * Amagi: Named for Mount Amagi in Izu, intended to be built at Yokosuka Naval Arsenal. Cancelled after earthquake damage and broken up in 1924. * Akagi: Named for Mount Akagi in Kantō, laid down at Kure Naval Arsenal. Converted into an aircraft carrier, serving as flagship of the First Air Fleet and participating in the attack on Pearl Harbor before being sunk at the Battle of Midway. * Atago: Named for Mount Atago near Kyoto, to be built by Kawasaki Shipbuilding Corporation in Kobe. Cancelled under the treaty and scrapped on the slipway in 1924. * Takao: Named for Mount Takao near Tokyo, to be built by Mitsubishi Shipyard in Nagasaki. Cancelled and scrapped incomplete in 1924.

See also

* Tosa-class battleship * Lexington-class battlecruiser * Number 13-class battleship * Japanese aircraft carrier Akagi * Washington Naval Treaty

Category:Battlecruiser classes Category:Cancelled battlecruisers Category:Military equipment introduced in the 1920s