When did submarines become a major threat to other subs?

Through World War I and II, you see surface ships and aircraft drafted/designed to fight submarines on the surface, and surface ships against submerged submarines.

Today, however, subs are used to hunt other subs, both underwater the whole time.

When did this transition take place? I’ve seen a few stories of WWII-era subs sinking other subs, but I always assumed (perhaps incorrectly) that those engagements were on the surface (well, at least one of the boats on the surface). My question is, when did the modern stereotypical subs-hunting-subs paradigm come into being? Late WWII, or was this purely a Cold War thing? Any naval officers back in that time write about the possibility, i.e. when was wholly-underwater warfare envisioned as likely, even inevitable?

Thanks much…

With the development of homing torpedoes, most likely. Wiki says that’s late WW2 for surface ships, so their development as sub-killers would be a Cold War item.

World War I and II subs were diesel electrics. They weren’t underwater boats. They were surface boats that could go underwater. Since they couldn’t run the diesels while submerged they were limited in how much time they could spend under the water.

With the invention of nuke subs in the 1950s, subs were no restricted by the life of their batteries with respect to how much time they could stay submerged. Modern subs can stay down for months on end. This led to the underwater cat and mouse games that modern subs play. Surface, land, and air forces do still play a major role in sub hunting. It’s just that now you’ve got other subs getting in on the hunting action as well.

Another change that factored into this was the fact that WWI and WWII subs were faster on the surface than they were underwater. Modern subs are faster while submerged. This change in hull design started happening at the end of WWII when longer range airborne sub hunters made it unsafe for subs to stay on the surface.

Per wikipedia

The duel between the HMS Venturer (P68) and U-864 on 9 February 1945 was the only time in the history of naval warfare that one submarine intentionally sank another while both were submerged.

I will not pretend any knowledge of this, but I have read Tom Clancy’s book, SSN. But I think engineer_comp_geek’s analysis is very reasonable. The traditional limitations, requiring a snorkel, etc. are removed in modern subs. So the next best step, i would guess, is to make these subs hunt other subs.

The Royal Navy had the beginnings of a sub designed to hunt other subs way back in WW1 the R Class.

Also, in WWII, hunting other subs would be a distraction from their primary mission, which was to starve out the other side by sinking their cargo ships. Spending time on anything other than that was contrary to orders, and to their basic purpose. Even sinking a battleship or carrier, while exciting to sub commanders, meant neglecting their basic mission. The real critical targets were oil tankers (at least in the Pacific).

Note that submarines were ranked according to the cargo tonnage that they had sunk. Thus USS Flasher is listed as the ‘top’ US submarine.

Those were designed for targeting surfaced subs, however.

Thanks for the learnin’. Didn’t know the story of the HMS Venturer, that was a new one to me.

This needs a little qualification: it wasn’t uniformly true that the “primary mission” of WWII submarines was anti-shipping. The relative priority of warship targets and shipping developed over the course of the war.

To generalize a little: the German navy started off with a firm focus on attacking shipping, the U.S. Navy assigned a high priority to warship targets at the start of the Pacific War, but soon realized the value of targeting shipping (and later focused this to put a high priority on tankers), and the Japanese Navy began and continued to prioritize warship targets over shipping–to the extent that, by the middle of the Pacific war, there was almost no threat to shipping between the continental U.S. and Hawaii, and so there were almost no convoys in that area (as sharply contrasted to the Eastern Seaboard, where U-Boats were aggressive, and convoys predominated).

In fact, one of the reasons that the Japanese Navy’s subs were relatively ineffective was that they were mainly sent out after warships, or to assist the surface fleet (for example, at Midway, where the IJN sub fleet was sent out as a “trap” for the U.S. fleet, and only succeeded in sinking an already-crippled Yorktown), rather than attacking shipping.

Of course, it’s a little more fine-grained than that–since the “mission” of a submarine might vary from patrol to patrol—but that doesn’t really affect the overall picture.

Here (http://www.navy.mil/navydata/cno/n87/usw/issue_12/rising.html) is a useful discussion of U.S. sub strategy, which points out that in the early pacific war,

While it is true that it was relatively rare in WWII for one sub to sink another while both were submerged, quite a few submarines were attacked and sunk by enemy subs while traveling on the surface. (and remember, WWII subs spent most of their time on the surface).

Examples to hand:

I-28, I-29

I-364, I-365, I-371 and I-373

Although the development of nuclear power plants and the associated endurance permitted longer patrols (necessary for naval superpowers like the United States and Britain), there are plenty of diesel-electric hunter killer (HK) boats that perform just as aptly at more limited duration regional patrol duty. The innovation that permitted submarines to become a serious threat to other (submerged) submarines wasn’t nuclear propulsion but the increase of capability in passive sonar which allowed subs to locate threatening subs and direct guided torpedoes to the target. The impetus for this development was, of course, to counter guided missile and (later) ballistic missile submarines deployed by the Soviet Union on deterrence patrols.

For the US Navy, the Barracuda-class subs were the first dedicated anti-submarine boats with an advanced acoustics suite (the BQR-4), although their range and endurance made them of limited operational effectiveness. The Tang-class subs were the first class of submarines that really filled the roll of dedicated sub-killers (intended to counter the converted Soviet Whiskey-class guided missile subs and Zulu-class ballistic missile subs and later the Golf- and Hotel-class boomers). The wide patrol limitations of the Tangs resulted in the use of nuclear powerplants in the Skate- and Skipjack-classes of HKs.

With the end of the Cold War and the lack of need to defend against regular deterrence patrols (the Russian Navy boomers spent a goodly portion of their post-Soviet years tied up to piers for lack of operating funds) the USN has been trying to convert attack subs to more multi-mission roles, including all-up cannisterized Tomahawks for ground-attack missions and more surveillance/sigint applications.


The change that made this happens was when the nuclear warhead equipped ICBM became deploy-able via submarine. Submarines then replaced aircraft carriers as the navy’s new capital ships (carriers having previously replaced battleships) because they then were now the most powerful weapon system on Earth.

Which meant that they were now the biggest and most important military targets on Earth. So an entirely new class of vessel, the attack sub, warranted being created with the specific design and purpose of being capable of destroying these apocalyptically powerful new subs if necessary.

As has been pointed out, having submarines hunting for submarines during World War II would have been a tremendous waste of resources. There’s a LOT of ocean out there, and sending out subs on seek-and-destroy-other-sub missions would have been a needle in a haystack proposition.

Moreover, there was no need to do so – a submarine a thousand miles from the nearest ship isn’t a threat to anyone. It’s only when it’s in proximity to a ship that the threat materializes, and there were more efficient ways of dealing with that threat (e.g. the convoy system). It was only when ballistic missile submarines became threats from anywhere on the planet that it became worthwhile to develop the ability to locate and hunt them wherever they might be.

Mention has to be made of the USS Batfish, which holds the record for most subs sunk by a sub (3). But they were all on the surface, so they don’t count towards the OP.