[ssmit132]

Can't forget the flaming pigs of old. Although according to that article it could have just been pig carcasses that were used.

[NGTM-1R]

...And, if you think about it, this really wouldn't have been the best anti-submarine weapon either, though I guess it might have been decent at hurling depth charges at long range.

The point was to be able to fling a significantly sized round to kill a submarine with a nearby detontation or a direct hit. (14.96" is the same size as the Bismark-class' main battery. This is not a small gun.) It's not as easy as it sounds, even considering water transmits shock much better than air. Dropped depth charges of about 600 pounds were only considered effective against most WW2 submarines if they detonated within twenty feet. (And after-action photographs as often as not prove that wasn't good enough.) Gunnery with HE shells of smaller size rarely even bothers a submarine; even direct hits from 4" and 5" HE were unlikely to do significant damage to the pressure hull as they detonated against the exterior hydrodynamic hull.

So if you want to kill a submarine with an explosive charge, you really have to work at it. The 14.96" Rakatenwerfer worked at it.

[Thaeris]

...At ranges of up to 6km, apparently. 

I don't know, I guess the idea of a submarine-based rocket mortar round (which would be an applicable weapon for a sub - getting a 15-in gun on a U-Boat is really not feasible) is more intriguing than the predecessor to the ASROC. The weapon certainly could have performed either function.

...The problem I precieve with using it as a depth-charge launcher is making the appropriate calculations for detonating the charge with WWII tech. Certainly, the technology was nothing to scoff at back then, but for this thing to be effective, you'd at least need an analog computer to account for flight time fusing delays, and then the sink rate of the rocket, for this to be effective in a timely fashion. However, analog computers were pretty common, so it might have not been terribly hard to deploy at all...

[Mongoose]

Can't forget the flaming pigs of old. Although according to that article it could have just been pig carcasses that were used.

Mmm, mobile bacon...