Japanese submarines and long lance torpedoes

I read recently about the Japanese long lance torpedoes and how deadly they were in battles off Guadalcanal, etc. The

Japanese never really used their submarines as an effective weapon against our merchant and US NAVY shipping in the

Pacific. On the US NAVY side ADMIRAL LOCKWOOD commander US submarines Pacific fleet put our submarines

on the offensive against Japanese merchant shipping and when we got our torpedo problems corrected in 1943 the

Japanese merchant fleet was destroyed by 1945.


gusord

 

Japanese submarine strategy, assuming they had one besides using them as fleet scouts, is one subject I would like to know more about, my understanding is the doctrine was to go after warships which are both harder targets and more likely to shoot back effectively with resulting high losses in subs. But while I have seen lots about the "decisive battle" against the USN battleline that dominated Japanese naval strategy I have found very little about submarine doctrine.
The building of a number of "headquarters" submarines makes me think they intended to create squadrons but what the squadrons were meant to do is unclear, there was no mass produced medium sized boat that would be required for merchant warfare.

 

In regards to the "Long Lance" or type 93 tropedo here's are some useful references:
http://www.navweaps.com/Weapons/WTJAP_Notes.htm
http://www.navweaps.com/index_tech/tech-067.htm
http://www.combinedfleet.com/torps.htm
http://www.combinedfleet.com/lancers.htm
http://www.navweaps.com/Weapons/WTJAP_WWII.htm
On Japanese subs:
http://www.combinedfleet.com/ss.htm
http://www.combinedfleet.com/sensuikan.htm
http://books.google.com/books?id=UFJdpxXkIBoC&pg=PA53&lpg=PA53&dq=japanese+submarine+world+war+2+doctrine&source=bl&ots=Aw-984eeId&sig=1G5UUKMj2k7i5qXZuhrmsc3a8mA&hl=en&sa=X&ei=Pj7zU7e3KsuhogTHjYDoAw&ved=0CDMQ6AEwATgK#v=onepage&q=japanese%20submarine%20world%20war%202%20doctrine&f=false
http://en.citizendium.org/wiki/World_War_II,_submarine_operations#Japanese_doctrine_and_equipment
http://www.nids.go.jp/english/publication/kiyo/pdf/bulletin_e2001_5.pdf
http://books.google.com/books?id=M-5feKonuNkC&pg=PA631&lpg=PA631&dq=japanese+submarine+world+war+2+doctrine&source=bl&ots=8q4lmYWChJ&sig=Z7pLiUoA2KC13X8A3EtvnVlYZYE&hl=en&sa=X&ei=aj7zU8yIJZChogST4YLoDQ&ved=0CFIQ6AEwCDgU#v=onepage&q=submarine&f=false
http://www.militaryhistoryonline.com/wwii/articles/strategiccultureijn1.aspx
http://www.ww2incolor.com/forum/showthread.php/6399-IJN-Submarine-Doctrine

 

Well, firstly the Japanese did not use the "Long Lance" Type 93 24-inch torpedo on their submarines. What they did use was the Type 95 21-inch torpedo, which was similar to the Type 93 - it kept the Long Lance's high speed, but had a slightly smaller explosive charge(893 pounds) and about 1/4th the maximum range(12,100 meters). Still, it was far superior to the American Mark 14 torpedo in all areas - speed, explosive charge, and range. As the Type 95 design was matured, the Japanese would reduce the maximum range to roughly 8,000 meters, but increase the explosive charge to over 1,200 pounds. The Type 95 design was further modified and resulted in the Type 96. This torpedo further reduced the range to 4,100 meters, but used a 36% oxygen mixture instead of the pure oxygen of the Type 95 to overcome the problems inherent in the use of pure oxygen(reliability, starting, and the torpedo's internal piping had to be kept totally clean of oil and debris).

The Japanese submarine were designed to follow the Japanese naval doctrine of using the submarines to support the fleet by reconnaissance and to attack American warships advancing to fight the intended "Decisive Battle". To this end, the were moderately successful early in the war - most notably; finishing off the damaged USS Yorktown at Midway, damaging the USS Saratoga twice, sinking the USS Wasp, sinking the damaged USS Juneau, and damaging the USS Chester, as well as sinking or damaging a handful of destroyers. However, there were a few notable failures as well, the most prominent being the failure to establish their submarine picket line in a timely fashion. However, this has been attributed to the fact that the picket line was composed of older boats that has been built in the late 1920's to early 1930's and were not quite up to the rigors of front-line combat. For reasons known only to the Japanese planners of Midway, the newer more capable submarines, not already deployed in the South Pacific, were assigned to support the invasion of the Aleutians, rather than being tasked with performing their intended role in the "Decisive Battle" at Midway.

The Japanese never focused their submarines against US merchant shipping effectively, because they had realized one salient fact(which most writers on the subject do not), which was that Japanese submarines would not be an effective weapon against US merchant shipping. They realized prior to the war that they could not hope to inflict critical damage on the US merchant fleet, and that it would be impossible for them to sink more merchant shipping that the US could not replace several times over. Thus, it would be a wasted effort to conduct a dedicated effort against the US merchant fleet. Sure, the submarines might enjoy some success, but no where near enough to win the war, or even substantially effect it's outcome. Therefore, their main concern remained focused on sinking US warships - which could not be replaced near as fast as the merchants could. Further, by reducing the number of American warships early on was part and parcel of their efforts to bring the Americans to the negotiating table.

Further along these lines, the Japanese, and the Americans for that matter, had not yet learned the lessons of submarine warfare that could only be taught by actual combat. Most, if not all, naval aficionados are well acquainted with "Paukenschlag" aka Operation Drumbeat - Germany puts 5 Type IX submarines off America's eastern seaboard, and they proceed to massacre American merchant shipping there. However, before the infamous "Paukenschlag", Japan had put almost double the number of German submarines into the busy American west coast shipping lanes - where they sighted few merchants, and sank only a handful of ships. The Japanese and their American brethren needed time and experience to learn the tactics that made the German submarines so successful. However, time was not what the Japanese had in their bid to win a "short" war.

 

There were only 4 "headquarters" submarines built, I-9, -10, -11, and -12. Two more were planned but cancelled in 1942, and two of a modified design were completed late in the war(I-13 and -14) and work on two more was stopped prior to completion(I-15, I-1).

These submarines were intended to act as HQ boats for a submarine squadron, while also being able to operate with said squadron at sea. Which was much more effective command-and-control than the previous use of submarine tenders and light cruisers as squadron HQ vessels - which would have great difficulty operating with the submarines at sea - either in action or on picket lines.

 

I thought I read somewhere, that the Bushido code came into play somewhat, that more honor was gained sinking a warship, than a cargo ship.

 

It was considered beneath the honor of a warrior to attack merchants, though some were hit during the initial stages. Even more deadly for the Japanese was their failure to consider the weakness of their ASW capacity.

 

I am uncertain as to how much "Bushido" plays a part in this as Japanese submarine success against merchant shipping is far greater than their success against warships. I can only wonder if Bushido was not a "myth" created by western writers to explain the failures of the Japanese submarine fleet to live up to western expectations based on American, British, and German success in this area of warfare.

 

I'm pretty sure it wasn't a myth on the other hand it's not clear how much impact it had. Certainly most navies gave more credit for sinking warships than merchants and at least my impresion is that when used in this sense credit and "honor" are pretty much identical. Along similar lines I remember reading that USN aviators noticed that their IJN opponents were more inclined to attack opposing fighters than attack planes unless the latter still had ordinance on board. There seems to me to be a pattern at least running through the background. Much of it also makes a certain amount of sense. I doubt it was an overwhelming effect but I suspect it was defintily there and influencing the perceptions of many naval officers perhaps without their even being concious of it.

 

The bottom line is that both the Germans and Admiral Lockwood who served in ww1 on subs realized that to strangle a nations life line and supplies for war was
to sink merchant shipping of the enemy. The US NAVY succeed in the pacific and the Germans attempted to succeed in the Atlantic [ almost did ].
By the way the US merchant marine suffered a very high casualty rate until the U boats were defeated by late 1943-1944-1945. One of the final blows was the
CVE jeep carriers that patrolled the central Atlantic known as the black hole. Planes flying around the clock and armed with search lights, depth charges, bombs
would catch the U boats on the surface charging their batteries. Also the US NAVY and the ROYAL NAVY formed hunter killer groups of destroyers, destroyer
escorts, and frigates whose main function with advanced ASW equipment was to take the offensive against U boats.
By the end of the war 75 % of U boat crews never returned.

 

So Bushido applied only to IJN, not the Army? That is interesting, how two different arms conducted themselves. The army was the bad guy/ navy good guy? Betting the class difference caused friction between the two.

Cheers, Gromit.

 

This task was made that much easier, because both of their intended targets were island nations that relied on merchant shipping for their "life line." Further, both island nations were some what limited, or in the case of the Japanese - very limited, in replacing their merchant losses. By the same coin, the United States was not in the same position. The US was not wholly dependent on her merchant fleet for national survival, and she could not only replace her merchant losses, but expand her merchant fleet, as well as, build merchant shipping for other nations, while at the same time expanding exponentially her own navy. As such mounting effective commerce warfare against the United States was an impossible task, and the Japanese realized this.

 

I'm not sure where you got that idea. Indeed I suspect that you could make a case for it being just as strong in the IJA as the IJN. There were good and bad and inbetween people in both services as well as in everybody elses military. Imperial Japan for some reason didn't seem all that concerned with the lives of individuals though. Population density may have had some impact on that cultural development but it's a topic I'd just be guessing at and not all that on topic for this thread.

 

Where did that come from? This is a thread about naval warfare, so i see no reason to include the Imperial Army since we're talking about submarine warfare.

 

I don't know if that's quite true. There are only so many ways for supplies to get from the US to Australia via shipping. If the IJN had set subs in the approaches to major Australian ports, like Darwin, Sydney, Perth, Melbourne and so on, a lot of damage could have been inflicted before allied ASW got up to speed. The idea is sinking cargo ships full of supplies, which would be done nearer Australia. With the bases the Japanese acquired in early 1942, the IJN could have easily positioned subs to patrol all the approaches to Australian ports.

 

IMO a determined but limited effort against merchant shipping by two or 3 flottilas that changed area of operations frequently would bring disproportionate results as they would force a strict convoy system with heavy escorts as a counter, and that takes up a huge amount of resources. But the Japanese were thinking/planning in terms of a limited war, economic warfare jut does not fit into their mindset, the last thing they wanted as to escalate the conflict to a life or death struggle they had no chance of winning (their big mistake was that PHd gave FDR a much support for the war as he could wish, they were probably hoping for something similar to Port Arthur that had the opposite effect on national will).
I do not know how targetting civilians fits with Bushido, but I believe it did influence the submarine tactics, on the other hand the Japanese were did use terror bombing (air attacks against cities designed to cause disruption) in China so ... I'm not sure.

 

Well, so the Navy could make "honourable" choices on who to attack, had never heard the Army being so picky with their prey...If Bushido only concerns the Navy- then my bad...Haven't heard of any stories of the Army giving a weak opponent a break...Pardon me if off topic.

 

I too feel that that the Japanese missed an opportunity to hurt us by declining to target our merchant marine. It's true that they couldn't bring us to our knees by such warfare, but had they been reasonably successful it would have slowed the build-up of our forces in the pacific. That in itself would have been helpful. Not only that, but as noted by previous posters it would have forced us to form an anti-sub force, including the inefficient convoy system, that would have also taken destroyers, jeep carriers, aircraft and command effort away from what we wanted to use them for. In short, it would make us react to their initiative and forced us to put resources other than our offensive efforts. Since the PTO was given considerably less resources than the ETO, this diversion of effort could have had significant ramifications for us. Would it have won the war for Japan? No, but it would have put a hurt on us and given us problems. Essentially, guerilla warfare, but guerilla warfare can have impact.

 

Could the Japanese really have fought a commerce war such as the Germans or Americans did? Very doubtful.

Germany essentially lacked a navy & merchant marine in World War II, and thus could focus most of her shipbuilding on her submarine fleet. The United States was the land of plenty, and could build am overwhelming number of everything her navy wanted. Japan could neither focus her navy, nor had the luxury of building everything she wanted. For instance, the Germans had in commission or commissioned 1156 U-Boats, or thereabouts, while for Japan that number was only 174. So, for Japan to fight a submarine commerce war on the scale of the Germans, she will have to drastically cut her shipbuilding of other classes of vessels. Could she cut production of battleships? Not really, the Yamato and Musashi are essentially complete, Shinano was about 45% complete when her conversion into an aircraft carrier began, and, finally, the unnamed Hull #111 had her construction halted and the scrapping process begun in December, 1941, when she was about 30% complete. Japan is going to need all the aircraft carriers she can get, and she knows this, so cutting aircraft carrier production is not an option. Japan never did build any heavy cruisers during World War II, so again, not an option. How about light cruisers? Well, Japan only laid down 5, and 3 of these had been launched by late 1942, so losing the Sakawa and Oyodo will only be but a drop-in-the-bucket...even less considering that Oyodo was intended to be a submarine flotilla flagship. Thus, any cuts will have to come where Japan can least afford it - from either destroyer/escort production or from merchant production.

Nor can Japan fight submarine commerce warfare such as the Americans did. While the Americans had significantly less submarines than the Germans did, they had many more than Japan(even more so if you include the number of cancelled Balao & Tench boats), and very few, the S-class & Catchalot class, were the effective equivalent of the more numerous RO & Ha submarine classes of Japan. Japan be facing an increasingly numerical and technologically superior US Navy, while at the same time being unable to replace the increasingly higher losses.

There were several ways to get to Australia, and at least two more in you include New Zealand's Auckland & Wellington. Even more considering the ports in the various island chains close to Australia. Then, you have to consider that Japan had some 63 ocean-going submarines(including 9 less capable RO boats). Now following the "Rule of thirds"(1/3 undergoing replenishment/refit, 1/3 traveling to & from station, and 1/3 on station, this leaves you with roughly 21 boats on station at a given time, then, you do have to consider that the some of the boats will be used on missions other than commerce warfare, this will leave you with far fewer boats on station off Australian ports, likely significantly less if you cover other ports in the "immediate" vicinity. Then given the abysmal performance of the Japanese submarines off Pearl Harbor and the American West Coast at the beginning of the war, I just cannot see the Japanese making "a lot of damage" during the critical stage of the Pacific War. At best, they cause a "scare", but this would probably lead to, and be corrected with, increased air patrols in the vicinity of Australian ports - where the water is shallow. Thus, forcing the Japanese submarines away from the Australian ports, therefore opening said ports once again.