Submarines of the Imperial Japanese Navy

The Imperial Japanese Navy (IJN) acquired its first submarines during the Russo-Japanese War on 12 December 1904 where they arrived in sections at the Yokohama dockyards.

The vessels were purchased from the relatively new American company, Electric Boat, and were fully assembled and ready for combat operations by August 1905.

In 1904 Kawasaki Dockyard Company purchased plans for a modified version directly from Holland, and built two boats (Hulls No.

The Kaigun Holland #6 was launched at Kobe on 28 September 1905 and was completed six months later at Kure as the first submarine built in Japan.

The commanding officer, Lieutenant Tsutomu Sakuma, patiently wrote a description of his sailor's efforts to bring the boat back to the surface as their oxygen supply ran out.

The sailors were regarded as heroes for their calm performance of their duties until death,[2] and this submarine was preserved as a memorial in Kure until the end of World War II.

Japan, along with the rest of the Allies, drew heavily upon Germany's Guerre de Course (commerce raiding) operations during the First World War, and their submarine successes reinforced Japan's willingness to develop this weapon, resulting in eighteen ocean-going submarines being included in its 1917 expansion program.

Japan received nine German submarines as World War I reparations, which allowed her and the other Allies to accelerate their technological developments during the interwar period.

Overall, despite their advanced technical innovation, Japanese submarines were built in relatively small numbers, and had less effect on the war than those of the other major navies.

Warships were more difficult to attack and sink than merchant ships, however, because naval vessels were faster, more maneuverable, and better defended.

Twice in the first year of the war, Japanese submarines torpedoed the aircraft carrier USS Saratoga, and, while not sinking her, put her in the repair yard at a time when the US Navy could ill afford to do without her.

Saratoga was torpedoed by submarine I-6 on January 11, 1942, putting her out of action and unavailable to participate in the desperate carrier battles and raids of the next five months, and then hit again three months after her return on September 1, 1942, by I-26, which put her out of action for another eleven weeks in the middle of the intensely engaged land-air-sea battles of the Guadalcanal Campaign.

A plane launched from one of the innovative aircraft-carrying submarines, I-25, conducted what remains the only ever aerial bombing attack on the continental United States, when Warrant Flying Officer Nobuo Fujita piloting a Yokosuka E14Y scouting plane dropped four 168-pound bombs in an attempt to start forest fires outside the town of Brookings, Oregon, on September 9, 1942.

Earlier in the year, in February 1942, the submarine I-17 fired a number of shells from her deck gun at the Elwood Oil Fields near Santa Barbara, California.

However, as fuel oil diminished and air superiority was lost, Imperial submarines were no longer able to continue with such successes.

Once the United States was able to increase its production of destroyers and destroyer escorts, as well as bringing over highly effective anti-submarine techniques learned during the Battle of the Atlantic, they continually took more and more of a toll on Imperial Japanese submarines, which also tended to be not as deeply diving as their Kriegsmarine counterparts.

One victory was the I-41 knocking the anti-aircraft cruiser USS Reno out for the rest of the war with a torpedo hit on November 3, 1944 (this was the first time in almost two years that a Japanese submarine had successfully attacked an Allied ship operating with a fast carrier task force[4]).

The Imperial Japanese Navy's doctrine of fleet warfare (guerre d'escadre) resulted in its submarines seldom posing a threat to allied merchant convoys and shipping lanes to the degree that the Kriegsmarine's U-boats did as they pursued commerce raiding against Allied and neutral merchant ships.

Early models of IJN submarines were relatively less maneuverable under water, could not dive very deeply, and lacked radar.

Yanagi missions were enabled under the Axis Powers' Tripartite Pact to provide for an exchange of strategic materials and manufactured goods between Germany, Italy and Japan.

The range and speed of these submarines was remarkable, 21,000 nmi (39,000 km; 24,000 mi) at 16 knots (30 km/h; 18 mph), but their underwater performance was compromised, making them easy targets.

These were fast, very long ranged, and carried a single Yokosuka E14Y seaplane, located in a hangar in front of the conning tower, launched by a catapult.

On 9 September 1942, I-25 launched its reconnaissance plane, a Yokosuka E14Y code named Glen which proceeded to drop four 168 pound bombs in a forest near present-day Brookings, Oregon.

They had a figure-eight hull shape for additional strength to handle the on-deck hangar for housing the three Seiran aircraft.

They displaced 1,070 tonnes, had a test depth of 360 feet (110 m), and were armed with four torpedo tubes and Type 96 25 mm (0.98 in) guns in retractable mounts to maintain streamlining.

They were high-performance boats, with streamlined all-welded hulls and a high battery capacity supplying two 2,500 hp (1,900 kW) motors, which had nearly double the horsepower of the German-designed MAN diesels.

Their Fiat diesel engines were unreliable, and like the F1 subclass they did not serve as the basis for future Japanese submarine classes.

The Kō-hyōteki (甲標的, Target 'A') class of Japanese midget submarines had hull numbers but no names.

The Kairyū (海龍, Sea Dragon) was a class of midget submarines designed in 1943–1944, and produced from the beginning of 1945.

The Kaiten (回天) was a torpedo modified as a suicide weapon, and used by the Imperial Japanese Navy in the final stages of the Second World War.