What if - Naval showdown in the English Channel

**Dreadnought** · 01 Aug 11,, 16:59

A little background on the depth of the Channel.

It is about 560 km (350 mi) long and varies in width from 240 km (150 mi) at its widest, to only 34 km (21 mi) in the Strait of Dover.[1] It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 km2 (29,000 sq mi).

It is relatively shallow, with an average depth of about 120 m (390 ft) at its widest part, reducing to a depth of about 45 m (148 ft) between Dover and Calais. From there eastwards the adjoining North Sea continues to shallow to about 26 m (85 ft) in the Broad Fourteens where it lies over the watershed of the former land bridge between East Anglia and the Low Countries. It reaches a maximum depth of 180 m (590 ft) in the submerged valley of Hurds Deep, 30 mi (48 km) west-northwest of Guernsey.

Grant it that depth could have varied since WWII but it also relays the point that in some areas you wouldnt want to take a sub and was prime for naval mine laying.

**zraver** · 01 Aug 11,, 17:14

Originally Posted by Genosaurer

No idea on the armor thickness or composition, info seems pretty hard to come by at least on the web. All I was able to find was a little blurb in Naval Weapons of WWII indicating that the coastal 40.6cm guns were emplaced in single "bettungscheiss-gerüst" mounts (?). But for argument's sake we can go with your numbers.

Using the people beside them to guauge thickness where the plates mesh up.

That said, even if they were completely unarmored and in open air pits, I don't really see how it would be relevant. It was demonstrated repeatedly in WWII that naval gunfire was almost entirely ineffective at knocking out coastal artillery.

Thats because most coastal artillery in WWII was bunkered Japanese or late stage Atlantic Wall fortifications. However in WWI, the allies did silence the guns guarding the Dardanelles before blundering in a minefeild.

Nor do I think in this scenario any Royal Navy ships would be attempting to duel the guns anyway - the focus would presumably be on the German transports attempting to cross the channel and their escorts.

I agree, but the RN does have the strength to do both.

The general assumption now seems to be that the Royal Navy would not risk sending battleships into the channel to oppose a crossing - that only cruisers, destroyers and MTBs would employed.

Faulty assumption, the Germans had good success with the Scharnhorst and Gneisenua vs transports let alone barges. I've talked about how barges would be swamped, but with transports the big shells water hammers will cave in thier sides and allow as much water in as a direct hit.

**Genosaurer** · 01 Aug 11,, 17:34

Originally Posted by Tarek Morgen

i am sorry but fredleander will not be able to answer any of your posts. After being given the choice of following the Forum-rules or be removed from WAB he chose the later option.

Unfortunate. I've always found it fun to play devil's advocate defending the more zany off-the-wall military history theories.

Originally Posted by zraver

Thats because most coastal artillery in WWII was bunkered Japanese or late stage Atlantic Wall fortifications.

There was a thread on this very board talking about the effectiveness of naval gunfire support - which I am now totally unable to find for some reason - that had some very good examples of the difficulty in knocking out even open-mounting shore batteries by bombardment. Will link when/if I can find it.

**zraver** · 01 Aug 11,, 18:22

Originally Posted by Genosaurer

There was a thread on this very board talking about the effectiveness of naval gunfire support - which I am now totally unable to find for some reason - that had some very good examples of the difficulty in knocking out even open-mounting shore batteries by bombardment. Will link when/if I can find it.

Please do becuase I think of two specific instances when it was very useful- Salerno and D-day. Although not engaging enemy artillery firing at them the NGFS proved decisive.

**Dreadnought** · 01 Aug 11,, 19:25

NGFS for the USN really didnt start to come about full time until after the BB's that were caught in Pearl Harbor were refitted. Most of your shore bombardment later in WWII was conducted by them with some instances being covered by the newer faster BB's.

It did however improve. Some even had FC computers specifically for this but not till later.

**Dreadnought** · 02 Aug 11,, 06:17

Originally Posted by Genosaurer

Unfortunate. I've always found it fun to play devil's advocate defending the more zany off-the-wall military history theories.

There was a thread on this very board talking about the effectiveness of naval gunfire support - which I am now totally unable to find for some reason - that had some very good examples of the difficulty in knocking out even open-mounting shore batteries by bombardment. Will link when/if I can find it.

All depends on the circumstances that prevail. Many factors to consider including range, accuracy, spotting, communications etc, and mission. There are also many instances of very good accuracy when you look at the numbers and what the missions were. What is/was the mission, destructive fire or interdiction?

In some ways you have already increased the chances of accuracy since you only have one moving variable (NGFS ship) while the shore battery is stationary in this particular case.

**Chogy** · 02 Aug 11,, 15:16

I have little real working knowledge of shore batteries vs. similar guns on ships, but I do have a theory. I'd welcome criticism of it.

Shore batteries were highly effective during the days of sail. Positioned over harbor entrances and heavily fortified with stone, big shore guns could deny a wide area to wooden sailing vessels. They could fire heated shot, could be much larger than ship-borne guns, and could be much better protected. Advantage to the shore guns.

Thus there remained a strong historic memory and tradition of shore batteries being effective and viable, and we know military institutions have huge inertia. Think Cavalry, which was obsoleted by Maxim guns but were still active up to WW2.

Along come dreadnoughts and excellent fire-controls, and the advantage possibly shifted to the ships, as they were mobile, and the shore batteries were not. Shore defenses continued to be built and manned, but the reality was, they were already obsolete and ineffective. They DID remain effective when engaging landing craft and invasion ships, but the traditional big gun ship-shore duels were no longer applicable. Thoughts?

**Dreadnought** · 02 Aug 11,, 15:53

There are many good examples of accuracy from the island hopping campaigns of WWII in the Pacific forward to the ME during Dessert Storm and the last roles they played.

Many good arguments made here on the WAB from some very good insight, there in effect lies the question, interdiction or destruction. Many variables when deciding which is called for and what orders are actually given as several conflicts involving them have shown in many different instances. Sometimes even the landscape itself either aids easy destruction or helps hide an enemy emplacement amking it more diffacult requiring more shots. Either way the larger guns tend to silence them even if for a brief period of time. And as many professionals here know, time is always of the essence when under fire.

**Tarek Morgen** · 02 Aug 11,, 16:26

Shore batteries were highly effective during the days of sail. Positioned over harbor entrances and heavily fortified with stone, big shore guns could deny a wide area to wooden sailing vessels. They could fire heated shot, could be much larger than ship-borne guns, and could be much better protected. Advantage to the shore guns.

Does the firm ground (in contrast to being on water) not also help with accuracy?

**wabpilot** · 02 Aug 11,, 17:55

Originally Posted by Tarek Morgen

Does the firm ground (in contrast to being on water) not also help with accuracy?

It does. We fired a lot of rounds and designed a very primative computer to increase the accuracy of naval gunnery based on those test fires. Still, similar guns assigned to the coast artillery are more accurate. With the advent of drones, we can now fly over the battlefield and call the shots of our naval guns. This and radar along with radar guided shells have greatly increased the accuracy of NGFS.

**USSWisconsin** · 02 Aug 11,, 19:39

16-in Guns vs Hard Targets : A Reality Check

this thread went into NGFS pretty deeply

**Genosaurer** · 03 Aug 11,, 03:20

Originally Posted by USSWisconsin

16-in Guns vs Hard Targets : A Reality Check

this thread went into NGFS pretty deeply

Thank you! This is the thread I was thinking of.

Originally Posted by Tarek Morgen

Does the firm ground (in contrast to being on water) not also help with accuracy?

Not only that, but shore batteries can mount larger rangefinders higher (since they don't have to worry about topweight or stability). All else equal, a shore battery should be considerably more accurate than a warship using the same type of gun.

**Dreadnought** · 03 Aug 11,, 04:15

Originally Posted by Tarek Morgen

Does the firm ground (in contrast to being on water) not also help with accuracy?

The diffaculty then (before the upgraded FCR and FC) was that for land based target you couldnt use radar to an extreme accurate point outside of reference points since it wasn't "height" finding. Spotting when accurate in air or on land and everyone is on the same page actually performs pretty well according to a few things I have read. Water is different, with a good set you get echoes from shell splashes and if your good walk it onto target.

**Dreadnought** · 03 Aug 11,, 04:42

Originally Posted by Genosaurer

Thank you! This is the thread I was thinking of.

Not only that, but shore batteries can mount larger rangefinders higher (since they don't have to worry about topweight or stability). All else equal, a shore battery should be considerably more accurate than a warship using the same type of gun.

Disagree, with the systems aboard even then should equal them and they can do it moving. Sure you can sucker punch them a few times, but once your locked on the results can be very different. Those gyros give the ship very good stability at being a stable gun platform.

This is a pic of Massachsetts in WWII at gunnery practice.

Remember, by the time that single battery shoots out rounds chances are that more then 17 times that many can be aimed at them. Battleships rarely concentrated all guns (that is both all main battery and secordary) and many times only the second battery at any single mount if they were in range for close in bombardment. It wouldnt make sense to offer the mount a broadside target when in many cases three sets of 5/38" or possibly even five sets (10 guns) could open up forward off the quarter and present only the bow of the ship in that direction but yet fire multiple projectiles as compared to the batteries single fire rate. The 5" could pump out anywhere from 11 to 22 per gun per minute.

In many cases if the mount was a known it wouldnt last too long. In most cases the guns would come out, open fire and then back under cover so they were diffacult to spot and therefore hit. Mounts dont have that option well atleast not the one that was pictured prior.

**USSWisconsin** · 03 Aug 11,, 05:57

The ability to mass tremendous fire didn't exist with shore batteries, but the Allies could bring in 20 or more battleships by mid-WWII and more than twice as many as Germany even in 1940, all with advanced fire control and giant fast firing guns, the very best shore batteries had higher elevation and larger charges - permitting longer range, though typically with lower rates of fire - but that was just a few guns (most shore batteries were smaller guns) - in response to this - mobile platforms like battleships and cruisers could bring as many as a hundred big guns to bear on a stationary shore battery target- with deadly accuracy. IMO, Had the Germans filled the channel with barges to invade Britain - the RN would have driven battleships and cruisers right though them firing with all tubes and small arms too - grinding them into splinters and red soup with their props. And the they would have hammered away at any surviviors coming ashore with their own shore batteries as well. It appears to me that Sealion would have been a blood bath for the Germans - unless they had total air superiority (like the Allies enjoyed over the channel in 1944-45) and had already reduced the shore defenses and the RN to ineffectiveness - which they hadn't been able to come close to doing in 1940.