a 1941 gun duel between a merchant and U-boat
 

From BdU's war diary the 3rd of July, 1941:

"U 69 sank in DH 19 a 5,000 ton ship (4 guns, 6 Flak machine guns) with artillery."

http://www.uboatarchive.net/BDUKTB30292.htm

uboat.net tells us there actually was a gun duel between the merchant and the type VII on a mining mission to Lagos, Africa

http://www.uboat.net/allies/merchants/ships/1028.html

I was under the impression that using guns in a situation where the u-boat could be shot at was a no-no. Apparently the order was not that strict. We of course don't know why the commander of U-69 decided to have a gun duel.

It would seem that he saw Robert L Holt in the afternoon and shadowed her until night, and made a surprise attack after the moon had set. It is possible that the crew of the Holt never actually had a target to shoot at.
http://www.u-boot-archiv-cuxhaven.de...rt_l_holt.html

I wasn't aware that there was an actual order against engaging with guns. I would think it was a matter of the fact that one hit on a submarine can render it no longer a submarine, but just a slow torpedo boat.

Thanks for the link! I was not aware that the museum's pages. They seem to have a lot of interesting stuff on them :D

U-boat commander's handbook has a few sections where it restricts the usage of deck gun.

BdU's war diary in late October 1939 has something on this too:

27.10
In order to lessen our losses and based on the reflections set out in the War Log on 23.10, I have decided to issue the following orders:

1) Boats may not board ships which have been stopped, for examination.
2) Ships are to be sunk by torpedo only, even when they are only attacked after examination (which can now only consist in looking through the papers) or after resistance has been quelled with gunfire.

I don't know what the wording of the order has been, but I suppose it has given the commander's some room to consider how, when and where they will use other armament than torpedoes.

The attack on Robert L. Holt might have been made without knowing how many guns the ship actually had but it seems that I might consider making some deck gun attacks against armed merchants from now on :arrgh!:

The U-boat may be an unsteady platform to shoot from, but on a very dark night it is also a tiny black target in a huge black ocean. If the captain of a U-boat thinks he can do enough damage and panic before the men can man the guns, a surprise attack could be deadly.

Many U-boat captains did finish off wounded ships even if their guns were still functioning - merchants sailors usually escaped the damaged vessel (or were too inaccurate to hit). The odds of hitting something that small, moving, and under constant fire was very low. One shot could destroy a U-boat, but it was very unlikely to hit one. Still, only the bravest risked it.

Well it worked for U-69! They were clearly weaker gunwise, but that did not matter after the surprise attack from close range.

I may be wrong, but I recall that someone (?Jimbuna) once stated that the merchant gun crews were in fact Royal Navy crews and not merchant sailors.:hmmm:

Oh, you're very right. If not RN then USN. Merchant gunners were their own division, and if you look through the ship reports at www.uboat.net you'll see many cases in which a u-boat attacked with its deck gun and then dove and ran when fired upon by the merchant. That was the norm, but there were exceptions. On a dark night the merchant as seen from below is a black outline against the sky. The u-boat as seen from above is, well, not seen at all. Suddenly the merchant is being shelled from out of nowhere. The gun crews have to get to their guns and prepare them. The loaders have to form the chain from the magazine to the guns. By that time they've taken several hits, and then they find they don't even have a target to shoot at except for the muzzle flashes in the dark, and when your eyes are looking at black on black a sudden flash is more likely to blind you than give you solid information on the target location.

Yes, a surprise attack at night can be devestating.

Very interesting thanks for the links. talk about a ballzy move

Thank you Sailor Steve for the very interesting Reading! :up:

A short but detailed information sheet on personnel manning "Defensively Equipped Merchant Ships (DEMS)" can be found here.

Clearly, these guys (and a few gals) were not untrained amateurs.

:salute:

An interesting document!

The uboat commanders handbook did label the uboat as a horrible gun platform and they are right! In the early war the gun was used to fire warning shots at merchants to get them to stop due to prize regulations. There were some commanders like Otto Kretchmer who was awesome at sinking ships with a deck very quickly, but he only attempted this in the dead of night! Outside of that, the handbook had specific ways to use the deck gun.

http://www.subsim.com/radioroom/showthread.php?t=219438

I doubt that's the case. If the gun is 40 feet in the air and trained flat the shell is going to hit the water in less than two seconds. The 4.7" DAMS gun had a muzzle velocity of 2330 fps, which means that it will hit the water at about 800 meters. The problem is that the 4.7"/45 could depress 10 degrees, which means that for it not to hit the U-boat is going to have to be right alongside. Most of the different DAMS guns were similar in elevation.

I think they just got surprised, the same as HMAS Sydney.