MovieChat Forums > Das Boot (1982) Discussion > WW2 U-Boat attack procedure?

WW2 U-Boat attack procedure?


SPOILER ALERT

I have a question about when the U-Boat attacks what they think is an unarmed convoy.

I was watching a documentary that said that the procedure for attacking unarmed and unescorted merchant ships was to order the crew to disembark before sinking the ship with the deck gun, whereas if the ships were armed or had an escort, they'd dive, fire torpedos and sink them that way with no warning.

In the film, the crew fires torpedos before they see the Destroyer - are they then technically breaking some kind of navy code. I don't remember they specifically stating the ships were unarmed but think they said something about them being "defenseless" or "unprotected"?

reply

In the film, the crew fires torpedos before they see the Destroyer - are they then technically breaking some kind of navy code.


No.
Your premise is wrong on several levels.
First off, the very basis of your belief is in error.

It is not some law of the sea that they can only use torpedoes on armed ships and must use the deck gun on unarmed.

The reason they would do it that way when possible to do so is twofold.
1) Using the deck gun when they can, saves the torpedoes for when they can't. Using the deck gun entails a very high risk to the sub and is very dangerous.
2) The German sailors were human beings too and not monsters like the Nazis. (Not all Germans were Nazis) If they had the ability to allow the crew to depart prior to sinking they would. In fact, they were well known to even provide food/water and even direction to the nearest land to the survivors of their attacks. Eventually culminating in the Laconia Incident where A German U-Boat which was rescuing the survivors of their own sinking was taken under attack by allied forces. This promoted BdU to give orders that forbade U-Boats from offering assistance.

So yes... The Germans would use the Deck gun IF it was safe to do so. It was only safe to do so however if the surface ship was unarmed and alone. Which meant that opportunities were rarer and rarer as the war wore on. Most shipping grouped together in escorted convoys, and even the rare independent steamer would likely have some sort of small caliber armament. Even that little bit however posed a great threat to a surfaced sub as any hole would prevent the sub from diving to safety.

It was not out of any sense of rules of war. Very early on there were such rules of warfare but very shortly into the war the Germans went to a doctrine of Unrestricted Submarine warfare.

Secondly... Even if your presumption of some rule was true, They were attacking an escorted convoy. There were enemy destroyers about even if none were spotted yet. In fact is was because none were spotted that the targets they were attacking were "defensless". Meaning the escorts were not in a position in the formation to be able to stop them. Not because they didnt exist. So any presumed rules on your part would still be proper.

A sub making a surface torpedo attack merely has to clear a few sailors down a single watertight hatch, flood the main ballast tanks and the negative ballast tank, close the main induction and dive. They could be underwater and fully submerged in about 30 seconds.

A sub requiring the use of the Deck gun has many more sailors out on deck through several hatches, the Gun itself rigged for firing, and additional hatches open for the ready ammo locker as well as the ammo train passing the rounds up from the inside from the main magazine. Attempting to dive in this condition would require several minutes, not 30 seconds. Suicide for the sub if there was a destroyer present.

I joined the Navy to see the world, only to discover the world is 2/3 water!

reply

Just one more thing...

There's no need for spoiler alerts on a 36 year old film.

I joined the Navy to see the world, only to discover the world is 2/3 water!

reply

I was watching a documentary that said that the procedure for attacking unarmed and unescorted merchant ships was to order the crew to disembark before sinking the ship with the deck gun, whereas if the ships were armed or had an escort, they'd dive, fire torpedos and sink them that way with no warning.


That's what they did at the beginning of WWI before unrestricted submarine warfare was introduced. Nobody did it in WWII. In WWI, the British started using Q-ships (decoy ships with the guns hidden). They would attack the U-boat when it surfaced, so the Germans started sinking ships on sight, without warning.

Surface raiders such as the Graf Spee would take off crews before sinking them but it was too risky for submarines to so that. Subs did use their guns to save torpedoes against small or "easy" targets.

reply

Subs did use their guns to save torpedoes against small or "easy" targets.



Yes - but it was risky business. Especially when The Allies got still more planes with still longer range and heavier bomb loads.
I have seen a photo of a gun crew, five men, with at least two men sitting on seats, from which they would have to climb, before escaping through the hatch. Compared to a man, already standing up, this would seem to last for hours and hours…. And they had lots of ‘no time’ when a Cat, a Liberator or a Sunderland came plunging out of the clouds
With a manned deck gun they would have a five-six man crew to escape ‘below’ and - not least - one more hatch to be closed before a crash dive could begin (very risky business to do that with the hatch open! )
My guess is that if it took fifteen seconds to clear the tower and the hatch to be closed, it may easily take some thirty seconds to clear the deck: I am sure that the gun would have to be locked in kinda ‘safe’ position and ammo brought ‘below’ or thrown into the sea.

reply

Also you have to consider that one of the ships in the convoy could have changed course and gone full speed in an attempt to ram and sink the submarine. There were case in World War 1 and 2 of ships ramming to sink submarines even though the ship sustained some damage to itself.

reply