Order of battle
Warships
IJN at time of Pearl Harbor Attack in December 1941:
Battleships
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 0 Yamato class (3 building (1 converted to aircraft carrier Shinano) and 1 cancelled later in 1941). Yamato — commissioned 1941, † 1945 Musashi — commissioned 1942, † 1944 The fourth of the class, Hull Number 111 was scrapped in 1942 when only 30% complete, and a proposed fifth hull, Number 797, proposed in the 1942 5th Supplementary Program, was never ordered.
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
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 (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.
Light cruisers
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 (1) 4 Agano and 2 Ōyodo (1 cancelled).
Destroyers
115 (plus 43 building) (1) 3 Momi-class destroyer (3) built 1920-1922 13 Minekaze-class destroyer built 1920-1922 6 Wakatake-class destroyer built 1922-1923 9 Kamikaze-class destroyer built 1922-1924 12 Mutsuki-class destroyer built 1925-1927 19 Fubuki-class destroyer built 1926-1933 (included Ayanami subclass) 4 Akatsuki-class destroyer built 1932-1933 (subclass of Fubuki class) 6 Hatsuharu-class destroyer built 1933-1935 10 Shiratsuyu-class destroyer built 1936-1937 10 Asashio-class destroyer built 1937-1938 19 Kagerō-class destroyer built 1939 4 Yūgumo-class destroyer built 1941 (1) 27 Yūgumo class and 16 Akizuki-class building (2) Others ships of the Momi-class were re-rated as patrol vessels. Also, note than Momi name was assigned in 1944 to a Matsu-class destroyer ship
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 4,250,000 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: