Imperial Japanese Navy - JUNSEN Type-1 Submarine ==========================================================================
Junsen type-1 submarines were large cruiser submarines of the Imperial Japanese Navy.
The Type 1 Junsen was built under German license to be an enhanced copy of a German design.
Between the years of 1925 and 1940 Japan developed it's submarine force. Their plan was to develop a submarine fleet on the basis of three types of boats. The first was a Cruiser-type submarine (Junsen) whose prototype was developed from designs of the British K Class and the German U-139 types of the First World War. They were to be used for reconnaissance and in operating far removed from base. The second was a long range or Fleet Type (Kaidai) which was developed from the preceeding type, but with a slightly increased displacement for co-operation with the surface forces and for patrolling enemy shipping routes. The third, a medium type was originally derived from the French Schneider-Laubeuf boats of the early years of the century.
The Junsen type boats were to have operated individually, replacing cruisers in the reconnaissance role (several were equipped with floatplanes), the Kaidai was intended to operate in flotillas, in direct co-operation with the main units of the Japanese Navy. Because of this, it lead to the surface designs of the boats being developed to the maximum extent; speed, seakeeping, range and gun armament and the resulting high displacement and dimensions, limited submerged maneurability and lengthened diving times. The effectiveness of American ASW measures was to prove fatal to these large Japanese boats.
When Japan attacked Pearl Harbor, the submarine force numbered 64 boats, 41 of which were of the Junsen Cruiser and Kaidai Fleet types, and two of the new medium types of recent construction, However, 21 were obsolete and were of little value during the attack. Additionally, about 20 boats of the three class types were currently under construction.
Beginning with the building of the first two prototypes between 1921 and 1922 which were derived respectfully from the British K class submarines of 1917 and the German U-139 type cruiser-submarines, also of 1917. The Japanese concentrated on the building of the Junsen type I class commissioned between 1926 and 1932 and followed by another two boats completed in 1932 and 1935, and the Kaidai type class of 1927 from which all the large cruiser and Fleet types derived. The normal displacement of the early Junsen types were of the order of 2,200 tons surfaced, and reached 3,000 tons submerged. Submerged speed was about 20/8 knots with a surface range of 20,000 miles at economical speeds.
These submarines were double-hull cruiser types, designed from the German U-boat cruiser-submarines of 1917. From the originial type (Junsen 1) whose prototype was laid down in 1923, three successive series were built between 1929 and 1938.
In most respects the Junsen type submarines were of poor quality. The large hull gave them excellent surface qualities, but greatly reduced their submerged manoeuvrability and their minimum crash-dive times were rather high. Their longe-range reconnaiassance use was limited and during the war they operated mainly as normal long-range attack boats. The eight boats of the Junsen type sank sixteen Allied ships totalling 87,744 tons and seriouly damaged another two ships. The I-6 seriously damaged the USS Saratoga close to Hawaii on January 11, 1942. None of these boats survived the war, the I-1, I-3, and the I-4 were lost between 1942 and early 1943, while replenishing garrisons in the Solomons.
The I-1 class version of the Junsen type was designed for long-range reconnaissance and for use ahead of surface battle forces. The ships in the class had a high surface speed, noteworthy for it's time. The four boats in this class were the first submarines in the Japanese Navy to mount 5.5 inch deckguns. Their performance allowed for patrols of 60 days. Maximum diving depth was 256 ft.
All Japanese submarines at the beginning of the war were armed with the most advanced torpedo of the entire conflict, the oxygen-propelled Type 95 21 inch, oxygen driven, wakeless torpedo capable of a run of 21,880 yds at the exceptional speed of 50 knots, or 40,000 yds at a speed of 36 knots, compared to the 15,316 yds at 28 knots and 6,126 yds at 45 knots of the American Mark XIV torpedo. The Type 95 was the submarine version of the very formidable 'Long Lance' Type 93 oxygen-driven torpedo carried by Japanese destroyers and cruisers which produced such excellent results in the battles for Guadalcanal and elsewhere. The Type 95 submarine version had a smaller 893-pound (405kg) warhead, less range, and a smaller diameter, and was intended to be fired from the standard 21-inch (533mm) torpedo tube of a submerged submarine.
With a top speed of 49-50 knots, the Type 95 was the fastest torpedo in common use by any navy at the time. Its warhead size was the largest of any submarine torpedo, and second only to the Type 93 'Long Lance' used by Japanese surface ships. Some have claimed these to be the best torpedoes of the Second World War.
During the war Japanese submarines sank 184 Allied merchantmen totalling 907,000 tons. They also sank numerous warships including the USS Yorktown, USS Wasp, and the USS Indianapolis. They also sank several submarines, miner and auxiliary vessels. Japanese submarine losses totalled 129 boats, 70 of which were sunk by surface ships, 18 by aircraft, 19 by submarine, and 22 others lost to various other causes. Losses and new boat construction were mutually compensating throughout the war. 126 submarines entered service between December, 1941 and August, 1945.
I-1 was present during the attack on Pearl Harbor, and shelled the harbor at Hilo. Later, she patrolled the East Indies, then witnessed the Doolittle raid on Tokyo, before patrolling the Aleutians.
These boats, based on the KD2 and U-139 designs, were of a junsen, or cruiser, type. Design endurance was 60 days and their range was an impressive 24,000 miles. Their MAN diesel engines, purchased from Germany, gave them a modest surface speed of 18 knots, although some of these boats exceeded 19 knots on trials. Already elderly by 1941, they saw some combat in the war, but were among the first Japanese submarines converted to supply duty.
Adapted to a cargo role, her aft 14cm gun was then removed to make room for a 46-foot daihatsu cargo barge and she started shifting supplies in the Solomon Islands.
On a supply mission to Guadalcanal, she was attacked by the New Zealand frigates Kiwi and Moa and, after a 90-minute battle, was rammed and wrecked in shallow water at Kamimbo Bay, Guadalcanal. She sank just off the beach on 29 January 1943. The crew took the current code books ashore, but left past and future codes aboard. Her bow remained out of the water, with critical codes on board. Tthe Japanese command tried unsuccessfully to destroy the boat by demolition, submarine torpedo, and air attack, but all attempts failed.
The US Navy managed to salvage the remaining code books, charts, manuals, and the ship's log, a total of 200,000 pages of intelligence booty.
The Junsen I-7 class submarines varied from the other submarines in the Junsen type, in that they were inspired by and developed from variants of the the Kaidai type. The two boats of the class (I-7, I-8) were the largest submarines yet built by the Japanese at the time of their commissioning before World War II. They participated in the attack on Pearl Harbor in patrol missions with their Yokosuka E14Y seaplanes being used in reconnaissance flights. The aircraft equipment was similar to that aboard the Kaidai but was ultimately not very effective. At the end of 1944 the I-8 had her aircraft arrnagements removed and replaced with equipment designed to carry four kaitens. Maximum diving depth for this class was 328 ft.
The Japanese submarine I-8 was a World War II Junsen Type J-3 Imperial Japanese Navy submarine, famous for completing a Yanagi technology exchange mission to German-occupied France and back to Japan in 1943.
Yanagi missions were missions enabled under the Axis Powers' Tripartite Pact to provide for an exchange of personnel, strategic materials and manufactured goods between Germany, Italy and Japan. Initially, cargo ships made the exchanges, but when that was no longer possible submarines are used.
Only six submarines attempted this trans-oceanic voyage during World War II: Kaidai I-30 (April 1942), Junsen I-8 (June 1943), the German submarine U-511 (August 1943), Kaidai I-34 (October 1943), and Kaidai I-29 (November 1943). Hei-gata I-52 was the final submarine to attempt the voyage (June 1944)
Commanded by Shinji Uchino, I-8 departed Kure harbor on 1 June 1943, together with I-10 and the submarine tender Hie Maru. Their cargo included two of the famed Type 95 oxygen-propelled torpedoes, torpedo tubes, drawings of an automatic trim system, and a new naval reconnaissance plane, the Yokosuka E14Y. A supplementary crew of 48 men, commanded by Sadatoshi Norita, was also packed into the submarine, with the objective of manning a German U-boat submarine (U-1224, a Type IXC/40 U-boat) and bringing it back to Japan for reverse engineering.
On arriving in Singapore nine days later, I-8 also took on board quinine, tin, and raw rubber before heading for the Japanese base at Penang.
On July 21, I-8 entered the Atlantic, where she encountered fierce storms, but was able to continue to German-occupied France.
Getting closer to Europe, on August 20, I-8 rendezvoused with German submarine U-161, commanded by Captain Albrecht Achilles. Two German radio technicians were transferred on board, as well as a FuMB 1 "Metox" 600A radar detector which was installed on the bridge of I-8. As I-8 entered the Bay of Biscay on 29 August, the Germans sent Ju-88s to provide air cover all the way to Brest, France, where she arrived two days later.
The Japanese submarine was welcomed warmly by the Germans. German news agencies announced that "now even Japanese submarines are operating in the Atlantic." Over a period of about a month, parties and visits to Paris and Berlin were organized for the crew.
I-8 left Brest on October 5, with a cargo of German equipment: machine guns, bomb sights, a Daimler-Benz torpedo boat engine, marine chronometers, radars, sonar equipment, anti-aircraft gunsights, electric torpedoes, and penicillin. The submarine also transported Rear Admiral Yokoi, naval attaché to Berlin since 1940; Captain Hosoya, naval attaché to France since December 1939; three German officers; and four radar and hydrophone technicians.
In the South Atlantic, I-8 hit rough seas off the Cape of Good Hope which delayed its arrival to Singapore. I-8 radioed its position to the Germans, but the message was intercepted by the Allies, prompting an attack by anti-submarine aircraft, which failed. I-8 arrived in Singapore on 5 December, and finally returned to Kure, Japan on 21 December, after a voyage of 30,000 nautical miles (56,000 km).
In late 1944, I-8 was converted to carry Kaiten suicide torpedoes. She was lost off Okinawa on 31 March 1945, in an encounter with the American destroyers USS Morrison and USS Stockton.
I-8 was also known to have been involved in some infamous war crime incidents :
On the 26 March 1944, during a raid into the Indian Ocean, I-8 torpedoed the 5,787-ton Dutch freighter SS Tjisalak. The submarine then surfaced amid the debris field and after a brief exchange of shots with the ship's defensive armament, collected the survivors upon the boat's deck. It was at this point, shortly after the freighter had sunk, that crew and passengers, totalling 97 survivors, were tied together and forced to run a gauntlet of Japanese sailors, during which they were slashed with samurai swords and beaten with monkey wrenches and sledgehammers before being shot, and kicked into the water. Six men somehow managed to survive this massacre and find a life raft, from which they were picked up by the Liberty ship SS James O. Wilder sometime later.
Just two months after the murder of the crew of the Tjisalak, the crew of the I-8 were involved in yet another atrocity, when they hit the 7,176-ton liberty ship SS Jean Nicolet with two torpedoes, not far from the scene of the sinking of the Tjisalak. The 100 crew of the American ship abandoned the burning craft and took to life rafts, but were all gathered on the submarine's deck in a similar fashion. This time the massacre took several hours, as the crew were made to walk individually past the conning tower, before being set upon and murdered. As this was going on, the crew were called back into the boat. Suddenly, and without warning the submarine dived, plunging the tied-up sailors still lying on her deck into the ocean where most drowned. Sources differ over the number of survivors, but it is believed that 22 men made it to a life raft, from which they were picked up by the HMS Hoxa some 30 hours later. Five prisoners were also taken to Japan by the submarine, one of whom survived to be released after the war.
I-8 also sunk numerous other ships, often with high loss of life, and some with total loss, suggesting additional war crimes which remain unknown. Her captain, who had encouraged and participated in the events, Tatsunoke Ariizumi, committed suicide at the Japanese surrender, and no charges were ever brought against the remainder of the crew, few of whom survived hostilities.
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NB: The above text has been collected / excerpted / edited / mangled / tangled / re-compiled / etc ... from the following online sources :
IJN - JUNSEN Type-1 class Submarine - www.combinedfleet.com
IJN - JUNSEN Type-1 class Submarine - warshipsww2.eu
IJN - Submarines of the Imperial Japanese Navy - www.geocities.com/bullhead262 - article#1
IJN - JUNSEN Type-1 class Submarine - www.geocities.com/bullhead262 - article #2
IJN - JUNSEN Type-1 class Submarine - wikipedia article #1
IJN - Submarines of the Japanese Navy - wikipedia article #2
IJN - Submarines of the Japanese Navy - wikipedia article #3
IJN - JUNSEN Type Submarine I-8 - wikipedia article #4
