The U.S. submarine campaign in the Pacific during World War II is well known. However, less is known about the Japanese anti-submarine force that faced the U.S. submarines during the war. Daniel Boustead tells us about the Japanese campaign here.
U.S. submarine ace Richard H. O’Kane (right) being awarded the Medal of Honor by US President Harry S. Truman (left) in March 1946.
During World War II, the Japanese had important wins against the Allies. These wins were attributable to some well-developed technology, weapons, and tactics. The Japanese were also helped along by several American blunders. The Japanese anti-submarine force was more effective than previously thought.
The Imperial Japanese Navy’s anti-submarine forces killed or captured two out three of the top three American Submarine Aces during World War II. The Japanese patrol craft P-34 captured top American submarine ace Richard H. O’Kane between October 24th and October 25th, 1944, when O’Kane’s sub-USS Tang was sunk by a circular run of its own torpedoes(1). O’Kane was the top U.S. Sub Ace with 27 ships sunk(11). He would end up at the Ofuna P.O.W. Camp and the Omori P.O.W. camp in Japan for the rest of the war(12).
The Japanese also killed Number 3 American Sub Ace Dudley “Mush” Morton on October 11th, 1943 after Japanese airplanes sunk Morton’s Sub U.S.S. Wahoo. A total of over 60 depth charges and 40 bombs were expended against the sub at the Le Perouse Strait(13). Dudley “Mush” Morton had sunk 19 Japanese Ships(14).
The Japanese anti-submarine campaign was beginning to have a negative effect on the American submarine crewmen’s morale. For example, U.S.S. Harder Exec Tim Lynch said of his skipper Sam Dealey “Sam was showing unmistakable signs, of strain,”, (15). Lynch continued, “He was becoming quite casual about Japanese anti-submarine measures. “Once, on the previous patrol, I found Sam in a sort of state of mild shock, unable to make a decision” (15).
Technology and tactics
By contrast the Allies were only able to capture or kill one out of three of Nazi’s Germany Top U-Boat Aces during World War II. The British captured Otto Kretschmer on March 17th, 1941, after the British Destroyer HMS Walker brought Kretschmer’s boat U-99 to the surface after a long depth charge attack(2). Kretschmer was the Third Reich Top Scoring Ace with 47 ships sunk. He sent 274,418 tons of shipping to the bottom(3).
A total of 52 out of 288 U.S. subs that were commissioned were lost by the end of war. By September 2nd, 1945, the loss rate was 18.06%(17). The Japanese sunk 41 out of 52 lost U.S. subs while they were on war patrol or due to enemy action. The other 11 were lost by various other causes.
The Japanese success can be attributed to technology and tactics. First, Japan’s radio direction finder network was very well developed(18). The Japanese were able to intercept almost all U.S. radio transmissions, except for very low or very high frequency calls. Thus, the Japanese could fix the position of a submarine transmitting on the surface within an area of about 100 square miles. This provided a means of keeping tabs on the U.S. subs in various areas, the number on patrol, and the general distribution in the Pacific. Japanese underwater listening gear was also excellent and echo ranging destroyers were always a threat to U.S. Subs. In the fall of 1943, the Japanese High Command organized the Grand Escort Fleet, along with an air escort squadron specifically designed to protect convoys against submarines.
By 1944, the Japanese radio detection system was growing more effective each month. Japanese Radio detection system was so successful it could intercept communications between subs in an American wolf pack. In addition, Japanese anti-submarine forces were now equipped with electronic devices that could sense U.S. radar beams coming their way and could therefore detect American boats in the vicinity. The effect of Japanese electronic devices forced O’ Kane to keep his radar searches to a minimum and then only in short bursts(16). This development compromised O ‘Kane’s stealth.
Lastly, by early 1944, the Japanese had depth charges with an explosive charge of 1,000 lbs. These weapons could be set to explode at depth exceeding 600 feet (17). In 1944, they were using new airborne radar in their night searches of U.S. subs. U.S. Subs were often subjected to night attacks by the Japanese while they recharged their batteries on the surface. Japanese planes carried standard bombs that were modified for use as an anti-submarine warfare weapon. Small planes were loaded with 150-pound bombs and larger aircraft dropped 625- pound bombs. The bombs were equipped with delayed-action fuses , which were set to explode at predetermined depth (16).
By 1944, the Japanese also began to organize anti-submarine air squadrons. The Japanese around the same time , were putting up extensive anti-submarine minefields. These were planted in the hundreds in many areas where a U.S. submarine would be operating. The Japanese mined these areas all the time. This made it very difficult for the Americans to locate the mines. During much of the war many submarines were lost trying to locate Japanese minefields. By losing a submarine, it was the only reliable way for them to locate a Japanese minefield (16).
American mistakes
Beyond the technology and tactics, the Japanese campaign was helped along by two important American mistakes. First, the Bureau of Ordnance made a fatal mistake right before the war. They did not test fire the Mark VI magnetic exploder, which was used on the warhead section of Mark XIV steam driven torpedo (4).The decision was made out of secrecy and as a cost cutting measure. The Bureau of Ordnance claimed that their Mark VI magnetic exploder would only need one to shot to work. In actuality, U.S. submarines would fire six shots directly at the target, and it would still not work. Instead, torpedoes, weighted down by the magnetic exploder would either run too deep, explode prematurely (because of the intense magnetic field of the target), or fail to explode if they reached the target. The magnetic exploder was at fault for the first two short comings, while faulty contact exploder pins were responsible for the last problem. Consequently, American submarines would pursue daring attacks, only to see their torpedo wakes bubble under a target or prematurely detonate, giving away their position (5). This problem was so bad that not until October 1943, over 21 months after the start of hostilities, could American submariners put to sea and know that their torpedoes would actually work (6).
Even after this point, there was still cases where there were fatal torpedo faults that would cost lives. American submarine torpedoes would sadly sometimes do a dreaded a circular run where they would turn back and hit their submarine instead of hitting the target. This was fatally demonstrated between October 24th and October 25th 1944 , when a circular of run of torpedoes sunk U.S.S. Tang commanded by top U.S submarine ace O’Kane (7). This incident was exploited by the Japanese Anti-Submarine forces who picked up O’Kane and his crew (8). According to what he told his Japanese captors, the Destroyer U.S.S. Pruitt and his first Submarine the U.S.S. Argonaut were equipped with equipment to prevent circular runs (9). However early in the war, for unknown reasons, the Bureau of Ordnance had done away with anti-circular run devices aboard American Submarines and American Destroyers. It was during O’Kane’s interrogation with his Japanese captors, that he stated his sub U.S.S. Tang was not the first victim of this fatal design flaw. Had the torpedoes been functioning properly the U.S. submarine force would have sunk more Japanese ships.
The second major mistake for the Americans occurred when an intelligence leak seriously compromised the secrecy of the U.S. submarine force. Congressmen Andrew Jackson May, a 68-year-old member of the House Military Affairs Committee, returned from a junket to the Pacific in the summer of 1943 and held a press conference (10). In that press conference, “He pointed out that the Japanese claims of sinking U.S. subs were overstated, because their depth charges were set to go off too shallow. U.S. subs could avoid them by diving deep, perhaps deeper than the Japanese thought them capable” (10). The newspaper reports of this catastrophic blunder reached Japan and its Navy reset their depth charges accordingly. The Commander of U.S. sub forces Charles A. Lockwood was enraged by this congressional leak. Privately, Admiral Lockwood blamed Congressmen May’s bombast for the loss of U.S. submarines and lives (10). An incensed Lockwood wrote to a colleague: “I heard Congressmen May say the depth charges are not set deep enough. He would be pleased to know (they) set them deeper now.” (10) Later Lockwood wrote, “I consider that indiscretion cost us ten submarines and 800 officers and men”(10). How deeply a U.S. Submarine could dive was a closely held secret prior to this incident.
Conclusion
The Japanese anti-submarine campaign had important successes owing to strong radio direction technology. They were also assisted by great weapons, tactics, and other technologies. However, they were significantly aided by U.S foibles. Ultimately, the end of the war was brought about with the atomic bomb attacks and the Soviet Intervention in the Pacific War. The Japanese surrender cannot be attributed to the American submarine campaign.
What do you think of Japanese anti-submarine warfare in World War 2? Let us know below.
Now, you can read World War II history from Daniel: “Did World War Two Japanese Kamikaze Attacks have more Impact than Nazi V-2 Rockets?” here, “Japanese attacks on the USA in World War II” here, and “Was the Italian Military in World War 2 Really that Bad?” here.
Bibliography
Gruner, William P. U.S. Pacific Submarines in World War II. San Francisco Maritime National Park Association-2010. https://archive.hnsa.org/doc/sbinpacific.htm.
Holwitt, Joel Ira. “Execute Against Japan”: The U.S. Decision to Conduct Unrestricted Submarine Warfare. College Station: Texas. Texas A& M University Press-William-Ford Military History Series. 2009.
Keith, Don. Undersea Warrior: The World War II Story of “Mush” Morton and the USS Wahoo. United States of America. Caliber Press. 2011.
Paterson, Lawrence. Otto Kretschmer: The Life of the Third Reich’s Highest Scoring U-Boat Commander. Annapolis: Maryland. Naval Institute Press. 2018.
Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006.
References
1 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 315-318 and 334.
2 Paterson, Lawrence. Otto Kretschmer: The Life of the Third Reich’s Highest Scoring U-Boat Commander. Annapolis: Maryland. Naval Institute Press. 2018. 194-204.
3 Paterson, Lawrence. Otto Kretschmer: The Life of the Third Reich’s Highest Scoring U-Boat Commander. Annapolis: Maryland. Naval Institute Press. 2018. 257.
4 Holwitt, Joel Ira. “Execute Against Japan”: The U.S. Decision to Conduct Unrestricted Submarine Warfare. College Station: Texas. Texas A& M University Press-William-Ford Military History Series. 2009. 162.
5 Holwitt, Joel Ira. “Execute Against Japan”: The U.S. Decision to Conduct Unrestricted Submarine Warfare. College Station: Texas. Texas A& M University Press-William-Ford Military History Series. 2009. 162-163.
6 Holwitt, Joel Ira. “Execute Against Japan”: The U.S. Decision to Conduct Unrestricted Submarine Warfare. College Station: Texas. Texas A& M University Press-William-Ford Military History Series. 2009. 163.
7 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 315-318.
8 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 334.
9 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 338.
10 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 164-165.
11 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 393
12 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 354 and 389.
13 Keith, Don. Undersea Warrior: The World War II Story of “Mush” Morton and the USS Wahoo. United States of America. Caliber Press. 2011. 263-268
14 Keith, Don. Undersea Warrior: The World War II Story of “Mush” Morton and the USS Wahoo. United States of America. Caliber Press. 2011. 312.
15 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 299
16 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 243-244.
17 Gruner, William P. U.S. Pacific Submarines in World War II. San Francisco Maritime National Park Association-2010. https://archive.hnsa.org/doc/sbinpacific.htm.
18 Tuohy, William. The Bravest Man: Richard O’Kane and the Amazing Submarine Adventures of the USS Tang. New York: New York. Presidio Press. 2006. 163-164.
