Chapter 10 Chapter 5 Actions of Submarines on Ocean Traffic Lines

As early as World War I, in order to force the Allies, especially Britain, to surrender, Germany implemented a strategy of sinking enemy merchant ships without warning, that is, conducting unlimited submarine warfare.After a long study, Germany decided to continue this strategy in World War II.However, this strategy failed both in World War I and World War II. The United States also adopted this tactic in its war against Japan, using submarines mainly to destroy Japan's maritime lines of communication, and achieved great results. Japan's strategy is to use submarines primarily to destroy the U.S. naval forces, and secondarily to destroy sea lines of communication.The main target of a submarine attack is the enemy aircraft carrier, followed by battleships and other naval vessels.Merchant ships were targeted only when no combat ships worth attacking could be found.Throughout the war, the Japanese naval authorities only allocated some submarines to perform the task of destroying the enemy's ocean communication lines without weakening the combat effectiveness of the fleet.

On December 10, 1941, I|6 reported that it was in Kauai Strait, southeast of Pearl Harbor, and found two American cruisers and a Lexington-type aircraft carrier sailing northeast.After receiving the report, the commander of the 6th Fleet stationed at the Kwajalin Base in the Marshall Islands immediately ordered the I｜9 (flagship), I｜15, I｜17, and I｜19 , Yi｜21, Yi｜23 and Yi｜25 pursue the enemy.At that time, the above-mentioned boats were all located in the waters north of Oahu Island in the Hawaiian Islands.In addition, Yi｜10 and Yi｜26 were also ordered to prepare for battle.The two submarines were deployed on the line of communication between Hawaii and the continental United States to intercept the enemy aircraft carrier, but they did not find the aircraft carrier.The boats ordered to pursue pursued them almost all the way to the American coast, but they never found the enemy.Therefore, they stayed in this sea area to perform the task of destroying the enemy's ocean communication lines.At this time, there are Yi｜9, Yi｜10, Yi｜15, Yi｜17, Yi｜19, Yi｜21, Yi｜23, Yi｜25 and Yi｜26 No. 9 submarines.They occupy positions along the U.S. coast from Seattle in the north to Los Angeles in the south.These submarines are of the latest type, with a surface displacement of about 2,000 tons (I｜9 and I｜10 have larger surface displacements), a surface speed of 24 knots, and an aircraft.

Combat activity by submarines against merchant shipping continued into the second half of December.By the end of December, the United States had greatly strengthened the anti-submarine alert of transport ships.During this period, Japanese submarines sank a total of about ten tankers and cargo ships.Like Yi｜24 (I served in this boat during the war against the United States), it went to sea to participate in the battle after refitting before the required long-term sea trial, and some machinery broke down as a result. When the war broke out, the Yi｜26 was in the position between the Hawaiian Islands and San Francisco. On the morning of December 8, 1941, it sank a 3,000-ton military transport ship with artillery, setting the first record for a Japanese submarine. one success.The boat then sailed to Vancouver, where it fired a torpedo at a merchant ship, but missed.According to the combat order before the war, the number of torpedoes launched against various targets was strictly limited: one for merchant ships and destroyers; three for cruisers; and for battleships and aircraft carriers, all the torpedoes on board as possible.In this way, the calculation of torpedo hits when attacking merchant ships is greatly reduced.Various experiments have shown that it is possible to hit a target when fired from a distance of no more than 750 meters, but that the probability of hitting a torpedo fired beyond this distance is very small.

On or about December 2, the I｜25 submarine, under the command of Lieutenant Admiral Tagami, approached ten nautical miles from the mouth of the Columbia River.The boat surfaced on a rainy night, spotted the 20,000-ton transport ship Connecticut, and attacked it.A torpedo hit, but the transport seemed unsinkable.The captain was about to launch the second torpedo when the transport began to sink.The crew of the ship returned safely to shore in a small boat, according to US radio broadcasts. On the 23rd, under the command of Major Lida Naval Commander, an old gunboat was bombarded on the water.The gunboat attempted to sail to Monterey Bay to escape pursuit.A shell damaged the rudder of the gunboat, and the gunboat ran aground because of loss of control.After firing a few more shells at it, the submarine left the area.

At the end of December, the Japanese submarine left the coast of the United States and returned to the Kwajalim base in mid-January 1942.On the way back, when Yi|25 passed between Johnston Island and the Marshall Islands, it found that several enemy radio stations were working, so it changed its course and sailed towards the radio stations. Before sunset on January 8, Lieutenant Takahashi, the duty watch officer, reported: An island was found!Further observation proved that what he found was not an island but a warship.Immediately the boat dived underwater, ready all torpedo tubes, and began approaching the target.Observations in the periscope confirmed that it was an aircraft carrier.The ship's derrick booms and flight deck lined with five aircraft can be seen.The aircraft carrier was parked at that time.Yi｜25 got very close to it, and then fired four torpedoes in salvo, all of which hit the target (Note: This situation has not been confirmed by the allies.).

At the end of January, the Yi｜8 submarine set sail to carry out the task of destroying the enemy's ocean communication lines, and arrived near San Francisco in early February.It cruises north all the way to Seattle.But not a single enemy ship was found either. In early March, the boat returned to Japan.I｜17 and another submarine were ordered to search for the enemy task force that attacked the Japanese anchorage of Kwajalin on February 2, but no enemy was found, so the I｜17 submarine sailed to the west coast of the United States, and on February 20 Arrive in the waters of San Diego.After bombarding the city of Santa Barbara (this bombardment has already been mentioned), the boat sank a merchant ship with a torpedo near San Francisco.But when it surfaced after the attack, it was shelled.It appears that the enemy's merchant ships have been armed.Yi|6 also sank an American merchant ship. At the end of March, it returned to Japan.Since then, activities to disrupt the ocean lines of communication along the coast of the United States have temporarily ceased.However, after that, there were still individual cases of sinking merchant ships; for example, after completing the mission of throwing incendiary bombs in the Oregon forest, the I｜25 attacked several ships along the northern coast of the United States in early October. Enemy ships, two tankers were sunk.Since then, when the boat continued to search for the enemy, it was also attacked by American bombers at an unfavorable moment.When the enemy plane attacked, all personnel on board, including those in the engine room, were on the upper deck. As soon as the submarine dived to a depth of 6 meters, the bomb fell.Fortunately, the explosion only damaged the antenna device, and the hole in the hull was not large.Yi｜25 continued to carry out the mission although it was unable to carry out radio communication.It was in the water north of Seattle and spotted two American submarines heading southeast.At this time, there was only one torpedo left on Yi｜25.It got close to the enemy boat to 450 meters, fired a torpedo, and hit an American submarine.With a violent explosion, the enemy boat sank to the bottom of the sea. (Jack's note: The original text said that Yi｜25 sank a submarine sailing on the surface within 500 meters. Because the distance was too short, the screws on the ship were shaken loose. It was later discovered that it was a Soviet submarine. Here it is said to be an American submarine. It may be that the Russian version has been concealed due to political factors.)

In late May 1942, while preparing for the campaigns in the Aleutian Islands and Midway, the I|25 and I|26 passed the coast of the Aleutian Islands, sailed to Seattle waters, and sank a ship near the Vancouver Strait. American transport ship. In 1943, since all submarines were concentrated in the Solomon Islands, they did not carry out any combat activities worth mentioning along the coast of the United States. In 1944, Japanese submarines achieved some victories along the coast of the United States, and two enemy ships were captured by Iraq. ｜No. 12 was sunk.But since February 1945, there has been no news of the submarine, and no one knows its whereabouts.

Judging from the above situation, the combat activities carried out by Japanese submarines along the coast of the United States were not large in scale, but their achievements were considerable. The Indian Ocean is also an operational area for Japanese submarines.After Japan occupied Penang on the Malay Peninsula, our submarines sailed into the Indian Ocean in January 1942 before taking Singapore, and began activities to destroy the enemy's ocean communication lines. Before 1944, enemy ships rarely passed through this area in convoys.Although the number of Japanese submarines operating here often increased or decreased as the situation changed, the attack on a single transport ship never stopped.According to the agreement reached between Germany and Japan, the boundaries of the two countries' submarine operation areas will change somewhat, but the area of ​​Japanese submarine operations has always included the entire Indian Ocean from the Arabian Sea to the coast of South Africa.The losses of Japanese submarines in the Indian Ocean were small, but the results were brilliant.This is the exact opposite of what happened in the Pacific Ocean.Therefore, all captains like to fight in the Indian Ocean.It should be admitted that I also have such a wish, but unfortunately my wish has never been realized.

Compared with the bases in the southern seas, the facilities in Penang are in every respect the best.The crew believed that compared with the bitter battle in the Pacific Ocean, the combat conditions in the Indian Ocean were as good as heaven. Here, enemy merchant ships were not guarded by warships, and it was not difficult to sink them.In order to save shells and torpedoes, some particularly courageous captains often surfaced, approached the transport ships, and burned them with gasoline.Most of these submarine captains were later killed in the Pacific Ocean. It can be seen from Attached Table 2 that Japanese submarines sank a total of 80 merchant ships in the Indian Ocean, and only lost two submarines, I-160 and I-34.I|160 was sunk by a British destroyer in the Sunda Strait, and I|34 was sunk by a British submarine near the Penang exit while sailing back to Japan in November 1943.

The operations of the submarines of the 8th Diving Team in the Mozambique Strait are considered to be the most effective.They have been active in this area for more than three months. In early August 1942, all submarines returned safely to Penang.At that time, two assault ships, Hokuni Maru and Aiguo Maru, equipped with torpedo tubes, cooperated with submarine operations.They were responsible for fueling the submarines, while also conducting combat activities of their own, sinking one and capturing one merchant ship. In 1944, despite the deteriorating situation in the Pacific, sabotage of enemy lines of communication continued in the Indian Ocean.However, the enemy has widely used the form of convoy convoys at this time, and the number of submarines we are fighting here is gradually decreasing.In this case, our losses start to rise. On February 11, 1944, Lu｜110 was sunk by an enemy gunboat near Vizagapatam in the Bay of Bengal; in the same month, I｜27 also disappeared.

In September 1944, the submarines operating in the Indian Ocean included Yi｜8, Yi｜37, Yi｜165, Lu｜113 and Lu｜115.But by the end of the year, they were all transferred to the Pacific theater one after another, and within the next six months, they were successively sunk by the enemy. Yi｜6 successfully deployed magnetic mines using torpedo tubes in the waters of the Port of Brisbane.The use of this mine was learned from the Germans.Each torpedo tube can hold two or three mines. The submarines Yi｜121, Yi｜122, Yi｜123 and Yi｜124 were all equipped with special equipment for laying mines.In addition to laying mines with the bow torpedo tube, the stern device can also be used to lay mines.These submarines were all built between 1925 and 1927, with a surface displacement of 1,140 tons and a surface speed of 14 knots. In 1940, gasoline tanks were installed on their upper decks, so they were able to perform the task of refueling the aircraft. The structure of these submarines is special, and the surface speed is very slow.Not easy to drive.They have small elevators and rudders, making them difficult to maneuver underwater.As long as the weight of the bow or stern of the boat is slightly changed, the submarine will pitch.If the weight of the boat is a little lighter, the submarine will float; if it is a little heavier, it will sink.Therefore, this submarine is very unpopular with the crew. In 1940, I served as mine chief on one of these submarines.After we lay mines at the stern, we must immediately inject seawater with a weight equal to the mines laid into the refill tank, otherwise the stern will surface.If too much water is injected, the boat will sink again.It is indeed a dangerous job to move forty-eight mines to the stern of the boat one after another, and at the same time inject seawater into the bow water tank to avoid trimming.The sudden movement of the position of the mine is often caused by the error of personnel movement or the poor balance of the boat, resulting in accidents and even casualties.When I was working on this kind of submarine, thanks to the skill of the helmsman (he has been working on the submarine for six years), no similar liability accidents occurred.It is extremely difficult to keep the submarine horizontally at the specified depth and lay mines accurately.Laying mines at the entrance of a harbor is usually required to be carried out when the tidal current velocity is two knots.When laying mines, the captain and navigator must coordinate to avoid dangerous mistakes. The mine-laying submarine team concentrated on Hainan Island before the war left the base on December 1, 1941. On December 8, I｜123 and I｜124 secretly laid forty sea mines at the western mouth of the Balabac Strait and near Manila respectively.After completing the mine-laying mission, Yi｜124 rescued several pilots who had crashed and fell into the water during the air raid on Manila, and reported the weather conditions to the base. On December 10, I｜121 and I｜122 laid mines in the Singapore Strait and sank a merchant ship trying to leave this area.Later, Yi｜123 laid mines at the northern mouth of the Surabaya Strait.Yi｜121 entered Manila Bay again, but was discovered by enemy patrol forces and failed to lay mines. In June 1942, after our failure in the Battle of Midway, in order to weaken the enemy's offensive spirit and improve the morale of our army, we attempted to carry out large-scale sabotage activities on the enemy's ocean communication lines in the Indian Ocean and Australia regions.But this attempt failed due to the enemy's counter-offensive in the Solomon Islands.In order to counter the enemy, most of our submarines had to be concentrated in the Solomon Islands.However, a small number of submarines remain in the Indian Ocean and Australian waters.For example, the 8th Diving Squadron used pocket submarines to attack enemy ships in the Port of Diego, Suarez and Sydney, Madagascar. After the Battle of Midway Island, the 3rd Diving Team began to operate in the communication line of Australian waters in mid-June.I|24 attacked a merchant ship anchored in Sydney during the night, but the attack was unsuccessful due to the premature detonation of the torpedo.The merchant ship was running at full speed in an attempt to escape.The captain ordered to float up and fired at the merchant ship, but there was no searchlight at night, so it was difficult to shoot accurately.Finally, a shell hit the merchant ship, the merchant ship stopped, and the crew boarded the boat.The captain originally attempted to sink the merchant ship with a torpedo, but intercepted the ship's call for help after being attacked, so he gave up the attempt. Torpedoes exploded prematurely, which has happened many times, because the sensitivity of the torpedo fuze was too high.Later, this shortcoming was overcome. After our withdrawal from Guadalcanal.The enemy's security force became more active, and our submarine losses increased.On the one hand, this is due to the development of the enemy's observation equipment; on the other hand, it is due to the weakening of our mothership aviation and the enemy's seizure of air supremacy.In addition, the enemy's transport ships began to sail along the northeast coast of Australia, which could be protected by the Great Barrier Atoll, and the submarine observation there was also very strict.Therefore, our submarine activities to destroy the sea communication lines leading from the enemy's rear to Guadalcanal and New Guinea did not achieve any significant results, although it was said at the time that the enemy planes were stopped at the Australian airfields for lack of gasoline.All in all, the odds are starting to turn against me.The 6th Fleet Command stationed at the Turuk Island submarine base has increasingly seen the seriousness of the situation.