Strength and organization of the Imperial Japanese Navy in December 1941 at the Pearl Harbor raid. Ships of the Combined Fleet and Japanese Naval Air Force.
Imperial Japanese Navy in WW2
Table of Contents
The Imperial Japanese Navy (IJN) played a significant role in World War II, particularly in the Pacific Theater.
Overview
Pre-war strength: By 1941, Japan had built the third-largest navy in the world, with a focus on aircraft carriers and battleships.
Pearl Harbor attack: The IJN launched a surprise attack on Pearl Harbor on December 7, 1941, bringing the United States into the war.
Early successes: The IJN achieved numerous victories in the early stages of the war, including the conquest of Southeast Asia and parts of the Pacific.
Aircraft carriers: The IJN relied heavily on carrier-based operations, with famous carriers like Akagi, Kaga, Soryu, and Hiryu.
Battle of Midway: This pivotal battle in June 1942 resulted in the loss of four Japanese fleet carriers, marking a turning point in the Pacific War.
Naval battles: The IJN participated in major engagements such as the Coral Sea, Guadalcanal, Philippine Sea, and Leyte Gulf.
Kamikaze attacks: As the war progressed, the IJN resorted to suicide attacks by pilots against Allied ships.
Technological innovations: The IJN developed advanced torpedoes, submarines, and the largest battleships ever built (Yamato-class).
Decline: The IJN suffered increasing losses as the war progressed, facing shortages of fuel, pilots, and ships.
Surrender: The IJN was effectively destroyed by the end of the war, with most of its remaining ships scuttled or surrendered to Allied forces.
The Imperial Japanese Navy’s initial successes and subsequent decline played a crucial role in shaping the course of World War II in the Pacific Theater.
Organization of the Imperial Japanese Navy
The Prime Minister presided over Imperial General Headquarters (GHQ) which was split in two sections – Army and Navy. Holding positions at Imperial GHQ were the Navy Minister and the Chief of the Navy General Staff, Admiral Osami Nagano. Other officers and departments handled the responsibilities of staff and ministry.
Executing the naval instructions emanating from Imperial GHQ was the C-in-C of all seagoing warships. This was Admiral Isoroku Yamamoto, and following his death in April 1943, his successors were Admiral Mineichi Koga, Admiral Soemu Toyoda (from March 1944) and Admiral Jisaburo Ozawa (from May 1945 to the end of the war).
In addition to the responsibility for implementing strategic moves generally, they were also expected to take tactical command of the most important operation in progress. Admiral Yamamoto flew his flag in the battleship Nagato until the super-battleship Yamato was commissioned on 16 December 1941. There was a constant restriction on radio communication whenever she put to sea, and at such crucial times, the C-in-C was out of touch with all but the immediate situation.
From May to September 1944, the C-in-C’s flagship was the Oyodo, a command cruiser for combined striking forces of submarines and aircraft. Although permanently anchored first in Tokyo and then in Hiroshima Bay, her communications facilities proved inadequate. The HQ of C-in-C Combined Fleet was finally located at Keio University in the Tokyo suburb of Hiyodashi.
As its name implies, the Combined Fleet (Rengo Kantai) was just that – the whole Navy. All other units, regardless of function or size, were designated as tai or butai, both of which could be translated as corps, force or body. The intelligence sections of other navies assigned the terms fleet, squadron and division for the purpose of description as appropriate.
It was customary for groups of smaller warships to be led by a bigger one. Thus, four destroyers made up a division, four divisions a destroyer squadron, plus a cruiser as flagship. A somewhat similar organization existed for submarines.
For administrative purposes, the Combined Fleet was divided into lesser fleets according to function.
Japanese Navy December 1941
Ships of the Combined Fleet:
Figures | Ship classes | under construction |
|
|---|---|---|---|
Battleships | 10 | 4 Kongo, 2 Fuso, 2 Ise, 2 Nagato | 3 (Yamato, one later as aircraft carrier Shinano)" |
Aircraft Carriers | 8 | 1 Hosho, 1 Akagi, 1 Kaga, 1 Ryujo, 2 Hiryu, 2 Shokaku (1941) | 8 |
Heavy Cruisers | 18 | 2 Furutaka, 2 Aoba, 4 Myoko, 4 Takao, 4 Mogami, 2 Tone | 1 |
Light Cruisers | 20 | 2 Tenryu, 1 Yubari, 5 Kuma, 3 Jintsu, 6 Natori | 9 (just 8 finish at the end of WW2) |
Destroyers | 108 | 3 Momi, 13 Minekaze, 7 Wakatake, 4 Kamikaze, 12 Mutsuki, 20 Fubuki, 4 Akatsuki, 6 Hatsuhara, 10 Shiratsuyu, 10 Asashio, 18 Kagero (1939-41), 1 Yugumo (1941) | 43 |
Submarines | 63 | ? |
Japanese Naval Air Force
Apart from 370 training and reserve machines, the Japanese Naval Air Force totalled approx. 1,400 aircraft. There were 660 fighters (mainly A6M Zeros), 330 carrier-borne strike aircraft, 240 twin-engined shore-based torpedo-bombers specifically intended for fleet cooperation, and 520 flying boats and seaplanes.
All these aircraft were organized in the Combined Air Fleet, based at Kanoya, and were subdivided into the 1st Air Fleet (the Carrier Fleet) and the 11th Air Fleet (under Vice-Admiral Nishizo Tsukuhura) shore-based in Formosa and Indochina. The fleets were further divided into air flotillas (each commanded by a rear-admiral), which were themselves composed of two or more air groups. Each air group comprised a base unit and 12 to 36 aircraft with 4 to 12 in reserve, depending on size. The combat formation was the air division of about nine airplanes.
References and literature
World War II – A Statistical Survey (John Ellis)
The Armed Forces of World War II (Andrew Mollo)
Fighting Ships of the World (Antony Preston)
Flotten des 2. Weltkrieges (Antony Preston)
Kriegsschiffe von 1900 bis heute – Technik und Einsatz (Buch und Zeit Verlagsgesellschaft)
Das große Buch der Luftkämpfe (Ian Parsons)
Battleships (ex battle cruisers) Kongo class were armed with 8 14-inch guns, i.e. 35,56 cm … The list is missing the battleships Kongo class (Kongo, Hiei, Haruna, Kirishima), Fuso class (Fuso, Yamashiro), Ise class (Ise, Hyuga) and Nagato class (Nagato, Mutsu).
Bibliography:
Breyer, Siegfried (1973). Battleships and battle cruisers, 1905–1970. Garden City, New York: Doubleday.
Conway’s All the World’s Fighting Ships, 1922-1946
Jane’s Fighting Ships 1922
Preston, Antony (1972). Battleships of World War I: An Illustrated Encyclopedia of the Battleships of All Nations 1914–1918. New York: Galahad Books
Rohwer, Jurgen (2005). Chronology of the War at Sea, 1939–1945: The Naval History of World War Two. Annapolis, Maryland: Naval Institute Press.
Skulski, Janusz (1998). The Battleship Fusō: Anatomy of a Ship. London: Conway Maritime Press
Whitley, M. J. (1998). Battleships of World War Two: An International Encyclopedia. Annapolis, Maryland: Naval Institute Press
In addition, the table missing 5 additional Kamikaze class destroyers …
In addition, 12 Kagero class destroyers are missing in the table, completed between 1939 and 1940
The title “Japanese Navy 1939-40” does not fit well here. To this, Soryu and Hiryu were treated as separate classes, both of which differed greatly. Under construction were two aircraft carriers (Shokaku class), rebuilding Takasaki for the Zuiho aircraft carrier ended on December 27, 1940. At the same time, started works on the completion of Junyo and Hiyo aircraft carriers, rebuilt from passenger ships Kashiwara Maru and Izumo Maru. November 15, 1940, the decision was made to rebuild Tsurugizaki on Shoho, but the work began in January 1941. Taigei was rebuilt to aircraft carrier from December 1941 to November 1942. In 1940 under construction were 5 aircraft carriers, less than stated in the table. The creator of the table forgot to add two heavy cruisers, Tone and Chikuma, completed between 1938 and 1939 and forgot mention the conversion of light cruisers Mogami class (4 ships) to heavy cruisers. Ibuki cruiser’s keel was laid on April 24, 1942. And there were 19 Fubuki destroyers, Miyuki sank on June 29, 1934 and did not survive until 1939.