The Imperial Japanese Navy of World War Two was one of the most powerful navies in the Pacific War if not the world during World War Two. During the first years of the war the IJN ruled the Pacific, however, it lost control and collapsed by the end of the war. It was contolled by the Imperial Japanese Navy General Staff and the Navy Ministry. The naval air service was one of the most potent air forces and ruled the skies over Asia and the Pacific for the early years.

Personnel Strength

• December 1941 - 291,359 including 1,500 pilots
• July 1945 - 1,663,223

Order of Battle

Warships

IJN at time of Pearl Harbor Attack in December 1941:

Battleships

• 10 (plus 3 building)(1)
  • 4 Kongo - converted from battlecruisers. Built in 1913-1915.
  • 2 Fuso - built 1915-1917
  • 2 Ise - built 1917-1918
  • 2 Nagato - built 1920-1921

(1)4 Yamato (3 building(1 Shinano converted to an aircraft carrier) and 1 cancelled later in 1941)

Aircraft Carriers

• 8 (plus 8 building)(1)
  • Hosho built in 1922
  • Kaga (ex-battleship converted in 1928)
  • 2 Hiryu built 1937-1939
  • 2 Shokaku built 1941-still on trials and workup.
  • Akagi (ex-battlecruiser converted by 1927)
  • Ryujo completed 1933

(1)Shoho and Zuiho converting from oilers.

Heavy cruisers

• 18 (plus 1 building)(1)
  • 2 Furutake built 1926-1927
  • 2 Aoba built 1926-1927
  • 4 Myoko 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 designed as light cruisers but altered to heavy cruisers while building.

Light Cruisers

• 20 (plus 9 building)(1)
  • 2 Tenryu built 1919
  • 5 Kuma built 1920-1921
  • 6 Natori built 1922-1926
  • 1 Yubari built 1923
  • 3 Jintsu built 1924-1925

(1)3 Katori(1 cancelled), 4 Agano and 2 Oyodo

Destroyers

• 108 (plus 43 building)(1)
  • 3 Momi(2) built 1920-1922
  • 13 Minekaze(3) built 1920-1922
  • 7 Wakatake built 1922-1923
  • 4 Kamikaze built 1922-1924
  • 12 Mutsuki built 1925-1927
  • 20 Fubuki built 1918-1931
  • 4 Akatsuki built 1932-1933
  • 6 Hatsuharu built 1933-1935
  • 10 Shiratsuyu built 1936-1937
  • 10 Aseshio built 1937-1938
  • 18 Kagero built 1939-1941
  • 1 Yugumo built 1941

(1)27 Yugumu class and 16 Akitsuki class building (2)Others of class rerated as patrol vessels (3)2 others of class converted to petrol vessels.

Submarines

• 68 Fleet submarines
• 50 Ko-hyoteki class Midget submarines

Others

• 90 patrol ships/gunboats/armed merchantships/ and submarine chasers,
• 6 minelayers,
• 42 minesweepers and
• 55 auxiliaries.

Merchant Ships

Many under direct navy control as armed merchantmen.

• 1939 - 2337 with 5,629,845 tons
• WWII 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 twin engine bombers
  • 520 Seaplanes and flying boats.