Imperial Japanese Navy of World War II

The Imperial Japanese Navy of World War II was the second most powerful navy in the Pacific War in World War II. It was the third largest navy in the world. During the first years of the war the Imperial Japanese Navy dominated the Western Pacific. However, after a series of defeats it lost control of the Western Pacific and collapsed by the end of the war. It was controlled by the Imperial Japanese Navy General Staff and the Navy Ministry. The naval air service was one of the most potent air forces in the world before its destruction in World War II. Nearly all were sent to the bottom of the sea by the war's end.

Personnel Strength

 * December 1941 — 291,359 including 1,500 pilots
 * July 1945 — 1,663,223

Warships
IJN at time of Pearl Harbor Attack in December 1941:

Battleships
(1) 4 Yamato class (3 building (1 Shinano converted to an aircraft carrier) and 1 cancelled later in 1941). Hull Number 111 was scrapped in 1943 when only 30% complete, and a proposed fifth hull, Number 797, proposed in the 1942 5th Supplementary Program, was never ordered.
 * 10 (plus 3 building) (1)
 * 4 Kongō class — converted from battlecruisers. Built in 1913-1915.
 * Kongō — †November, 1944
 * Hiei — †November, 1942
 * Kirishima — †November, 1942
 * Haruna — †July, 1945
 * 2 Fusō class — built 1915-1917
 * Fusō — †October, 1944
 * Yamashiro — †October, 1944
 * 2 Ise class — built 1917-1918
 * Ise — †July, 1945
 * Hyūga — run aground in July, 1945
 * 2 Nagato class — built 1920-1921
 * Nagato
 * Mutsu — †June, 1943
 * Yamato — commissioned 1941, † 1945
 * Musashi — commissioned 1942, † 1944

Aircraft carriers

 * 6 heavy and 6 light (plus 7 building )(1)
 * Hōshō built in 1922
 * Akagi (2) (ex-battlecruiser converted by 1927) — †1942
 * Kaga (ex-battleship converted in 1928) — †1942
 * Ryūjō completed 1933 — †1942
 * Sōryū — †1942
 * Hiryū — †1942
 * 2 Zuihō class commissioned as aircraft carriers 1940-1941
 * Shōhō - †1942
 * Zuihō - †1944
 * 2 Shōkaku class built 1941
 * Shōkaku — †1944
 * Zuikaku — †1944
 * 3 Taiyō class
 * Taiyō — †1944
 * Chūyō — †1943
 * Unyō — †1944
 * 2 Hiyō class
 * Hiyō — †1944
 * Jun'yō
 * Shinano (ex-battleship converted in 1942-44) — †1944


 * (1) Does not include Imperial Japanese Army built aircraft transports.
 * (2) Amagi — sister ship to Akagi both as a battlecruiser and as a conversion to an aircraft carrier, was destroyed during construction by an earthquake and replaced with the Kaga.

Heavy cruisers
(1) ''Ibuki ordered but not laid down (2) Mogamis designated light cruisers but were built to be up-gunned as heavies once the London Naval Treaty was broken.
 * 18 (plus 1 building) (1)
 * 2 Furutaka built 1926-1927
 * 2 Aoba built 1926-1927
 * 4 Myōkō built 1928-1929
 * 4 Takao built 1932
 * 4 Mogami built 1935-1937(2)
 * 2 Tone built 1941

Light cruisers
(1) 4 Agano and 2 Ōyodo (1 cancelled).
 * 20 (plus 5 building) (1)
 * 2 Tenryū built 1919
 * 5 Kuma built 1920-1921
 * 1 Yubari built 1923
 * 3 Sendai built 1924-1925
 * 6 Nagara built 1922-1925
 * 3 Katori (1 cancelled) built 1938-1940

Destroyers
(1) 27 Yūgumo class and 16 Akatsuki class building (2) Others of class re-rated as patrol vessels (3) 2 others of class converted to patrol vessels
 * 126 (plus 43 building) (1)
 * 3 Momi-class destroyer (2) built 1920-1922
 * 13 Minekaze-class destroyer built 1920-1922
 * 7 Wakatake-class destroyer built 1922-1923
 * 4 Kamikaze-class destroyer built 1922-1924
 * 12 Mutsuki-class destroyer built 1925-1927
 * 20 Fubuki-class destroyer built 1926-1933
 * 4 Akatsuki-class destroyer built 1932-1933
 * 6 Hatsuharu-class destroyer built 1933-1935
 * 10 Shiratsuyu-class destroyer built 1936-1937
 * 10 Asashio-class destroyer built 1937-1938
 * 18 Kagerō-class destroyer built 1939
 * 19 Yūgumo-class destroyer built 1941

Submarines

 * 68 Fleet submarines
 * 50 Ko-hyoteki-class midget submarines

Others

 * 90 patrol ships, gunboats, armed merchant ships, and submarine chasers
 * 6 minelayers
 * Itsukushima
 * 42 minesweepers
 * 55 auxiliaries

Merchant Ships
Many under direct navy control as armed merchantmen.
 * 1939 - 2,337 with 5,629,845 tons
 * World War II construction of 4,250,00 tons
 * 2,346 sunk

Aircraft

 * Total 1750 first line with 370 trainers
 * 660 Fighters
 * 330 Carrier based strike aircraft
 * 240 Land-based twin engine bombers
 * 520 Seaplanes and flying boats.

Commanders
Imperial Japanese Navy commanders at the time of the Attack on Pearl Harbor: